Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

It's in decent condition, new rubber impeller, scraper bar and overall good shape. The guy I bought it from said it had been professionally serviced 2 years ago but had seen little use since then as he decided to hire a plow guy to do his average residential driveway. I could not get it to start after adding some fresh fuel that I brought with me so I offered him $ 40.00 and said OK. - he had it listed for $ 75.00 on CL. I'm pretty sure he left some old, unstabilized fuel in there and it turned into varnish.

I removed the top and back covers and dropped the fuel bowl. It looked like a bad batch of applesauce in there so I cleaned it out and shot the carb with carb cleaner and reinstalled the bowl. It fired up for a few seconds and then died. A good carb cleaning appears to be in order and I'm wondering if I can do this with the carb installed or is it easier/better to remove it from the engine (Suzuki 47P)? I've never removed a carb before but am mechanically inclined and would like to get this operational for next winter.

I remember Borat discussing a cleaning of the jets using wires to remove any build up inside that could cause fuel starvation. I have never done this so any suggestions or tips will be very much appreciated.

Nice score for $40.  Even if you need a whole new carb, it's still a good deal.

Remove the sparkplug add a teaspone of gas put the spark plug on and it should start in a few pulls, if it starts and stops do this a few times and you may get lucky the engine may suck out all the dead gas. Next step remove the carb. bowl clean the jets and you are good to go.

If you have the tools to remove the main jet, you should be able to take it out without removing the carb.   Drain enough fuel from the tank to allow you to tilt the machine forward.  Remove the float bowl.  If the float is circular with a hole in the center, you should be able to access the main jet.  It may have a hex head or a slot for a screw driver for removal purposes.   If it has both, use the hex.  If it just has a slot, make sure you use the correct size screw driver and be very careful not to strip it.  The jets can be in there fairly tight.    Remove the jet and clean it.  Spray carb cleaner into the hole where the jet goes.  Use a thin wire and clean all orifices you find.  Flush with carb cleaner and blow out with compressed air. 

While you have the float bowl off, you might as well remove the float and clean the float needle and seat.  The float is usually held in place by a friction fit pin that comes out fairly easily.  Watch out for a very tiny wire clip/spring that might be on the float lever.  Take a good look and maybe a picture of how it all goes together.   When you have the float and needle removed, pull the fuel line off of the fuel tank a blow compressed air into the fuel line to clear the line and float needle seat.  Inspect the float needle, use a Q-tip and carb cleaner to clean the float needle seat.   Be very careful when working with the float.  You don't want to bend the lever and put the float out of adjustment.

Re-assemble.  I bet it will run fine.

borat wrote:

This sounds like the arrangement that I have on this engine. I will remove the main jet and thoroughly clean as suggested. I've been able to get it running for about a minute after several attempts using edgenets suggestion of a teaspoon of gas down the spark plug hole.

I appreciate all your input and know that I will get this fixed with your help.

Thank you!

Frank 

Well I have been working on this off & on for a few days now and still can't seem to keep her running for very long. She'll turn over and run sometimes for up to a minute or so and other times just for a few seconds. I've cleaned the carb as suggested by borat (it was exactly as you said it would be) and hosed everything down with carb cleaner. This really seemed to remove a lot of garbage, especially when I removed the float and needle and gave it a good blast of carb cleaner. I'm going to give it another good cleaning, reassemble everything and see if this does the trick. I'm getting there slowly - any other suggestions are welcome.Thanks again for your help. 

Frank- Change the fuel line which may have deteriorated and flush the tank. While you are at it if there is room I would install a fuel shut off valve.

Marc 

mml4 wrote:

Thanks Marc. All of the above is going to be my next step. I noticed the fuel line looked a little suspect when I replaced the fuel filter but did not have the correct size fuel hose to replace it with at the time. Off to get some parts and will hopefully have some good news to report later.

Have you removed the carb to clean it?  If not, you should.  There are some very tiny holes in the carb venturi that need the wire treatment and flush. 

With intermittent running, it sounds like you have fuelus interruptus.  

Start at the fuel tank.  Take a good look inside for dirt or take it off the machine and flush it out.  Closely inspect for an interior fuel filter (probably not) and make sure the fuel system from the tank is clear.  A new fuel line won't hurt.  Once you know you have positive fuel flow to the carb, you can then concentrate on the fuel systems inside the carb.  Can you tell if the engine is either starving or flooding?   If it's flooding, your float might be defective.  If it's starving, I suspect it's the very fine orifices and/or galleries within the carb.   Taking it off, cleaning with very thin flexible wire, flushing with WD-40/carb cleaner then blowing out with compressed air should get it running right.  

Keep us posted on how it goes.

  Pulling the carb should be easy.   If I remember right the carb on those are on standoffs and have just enough governor rod length to allow it to slip over the studs.   Given the appesauce a dip might be helpful ($20 for Berrymans at Autozone).  The float level could be messed up.  

l would install a new needle and seat, just to rule out that its not sticking closed and starving the engine of fuel, but most imporantly l would make sure the FLOAT is adjusted properly and not sitting too low in the bowl. make sure its level with carb base when upside down.

Well here is where I'm at with this project. I've replaced the fuel filter, fuel line, primer bulb (it was missing) and feed line, drained and cleaned the fuel tank, new spark plug, cleaned the carb several times and replaced the float bowl gasket. The engine will run for a few seconds and then die, afterwhich I cannot get it started again. I continue to find debris in the float bowl when it's removed for inspection after each failure to start. I replaced the float bowl gasket after finding that it was stretched out enough to not seal the bowl - thought I had my fix after finding this but it still won't stay running.

I'm thinking that if I just keep at it and maybe add some fuel in the spark plug hole, that it will eventually flush out whatever debris is causing the problem. I'm also thinking that trouts and borat are correct in suggesting that I drop the carb and give it a thorough cleaning and a dip in some Berryman's - maybe even replace it if neccessary. I'm only into this for about $ 60.00 at this point so I'm far away from the point of no return. The teaspoon of fuel in the spark plug hole has produced that best results in terms of run time - up to about a minute before it died. 

Do you think I should keep trying to get it running via the teaspoon of fuel method and possibly flush out the problem (pun intended) or drop the carb and clean with wires and a Berryman's dip? Where are the holes/jets located that I should clean with a wire? I did remove and clean the jet located inside the main jet orifice, dropped the float and needle, cleaned both and reassembled and have spayed the entire carb inside and out with copius amounts of carb cleaner.

Where could the dirt and debris be coming from if you cleaned the fuel tank and replaced line and filter?  Can't get my head around that.  You have to determine where the dirt is coming from.

If the engine runs with fuel dumped into the cylinder, it appears that the engine is experiencing fuel starvation.

Pull the carb off.  Get a very thin piece of wire about the size of a stripped trash bag tie wrap.

Look into the big hole of the carb throat (venturi).  Look very closely on the bottom for a very tiny hole(s) just a bit bigger than the diameter of the wire feed the wire into it to clear it.  Remove the main and pilot jets.  The pilot should be a small brass insert with a slot in it somewhere beside the main jet location.  Try to feed the wire in there and flush with WD-40.  If you have compressed air, use a rubber tipped adapter on the air nozzle to make a seal.  With the jets removed, blow air into the main and pilot jet holes.  Flush with WD-40 and blow some more.  Look for air/oil to come through that tiny hole in the venturi.   Make sure to carefully remove the float assembly before doing any of the above.  Once the carb is properly cleaned, it should run like a top.

Frank >>>I continue to find debris in the float bowl. Often there is crud in the tank and it's screen defective or the line no good and particles breaking off the line. Pull the line at the carb and run water through the tank or gas to a container and run that through several times. Once there were some sort of grubs in the line or tank that died. The carb would be cleaned and the bowl would later get crapped up. This happened a couple of times. The gas would soften them and they would break up into small particles which got into the bowl.

OK I know I'm just repeating what's been said already, but you had to have (OK, 98% chance) missed something ... "I've replaced the fuel filter, fuel line, primer bulb (it was missing) and feed line, drained and cleaned the fuel tank, new spark plug, cleaned the carb several times and replaced the float bowl gasket." Did you remove the fuel tank and clean it good? Inspect inside with a good flashlight? Check the cap, make sure the pieces inside are not disintegrating. Is there a screen in the outlet? (I'd rip it out and toss it, just have a good fuel filter) Also, look inside your gas can! Any possibility you have good gas but maybe some dirt in the can? (and if so, why didn't the filter catch it?) You're not getting fuel into the cylinders. Usually this is a carb problem. There's a (very very) tiny chance you have a valve problem but I'd look at the fuel system again first. You are getting dirt in the carb. Where is that dirt coming from? Pieces of the old primer bulb? If you're positive the line, filter, tank and anything else that gets near the fuel before it reaches the bowl are 100% clean, then I'd pull the carb for a thorough cleaning. And I don't mean to insult you, but we've all made silly mistakes ... you didn't accidentally reverse the fuel filter, did you? It's just that so often the really nasty head-scratchers have very simple answers.

I'm going to go through everything again to be sure I covered all my bases. I did drain and remove the fuel tank and sprayed the inside with carb cleaner and let it drain into a clear container - it was pretty clean. I will also reverse the fuel filter as I put the new one on in the same configuration as the old one but that's not say the old one was installed correctly. Those little fuel filters don't have a direction arrow on them and I had considered reversing it just to be sure - it's a plausible reason for fuel starvation (thanks Bill_H). If all else fails, I'm going to remove the carb and give it a thorough cleaning as suggested earlier by borat and trouts.

I believe it's definitely being starved of fuel because if I add a teaspoon or so of fuel directly into the cylinder, it will start up for a bit and then die. I can't restart it again unless I add more fuel to the cylinder. The good thing is it turns over and starts so I think if I can work through this problem and get her going, I will have myself a decent CCR3000 for short $$$. Many thanks again to all who have offered advice.

l would perform a pressure check on the crankcase and make sure there no leaks. u will need a pressure tester to do this, add about 7psi and let sit for 5-10 min and see if there a drop in pressure if so use soap and water and check all gaskets for the leak. if u have a leak u may need to pull off the flywheel to get at the crankseals but check everthing else first....make sure the piston is at BDC push it down with a screwdriver till its at the bottom. heres a video of guy showing how to pressue test the crankcase..searchthis name "areomyst" on u tube.

Personally, I doubt it a seal issue.  Seems like a straight forward, fuel starvation problem.   Carb isn't properly cleaned. 

If he were getting fuel, the engine will probably run just fine.   If the engine gets fuel and has a leaking crank seal, it will probably run away on him.  Seen it happen....... more than once. 

I have not had any time lately to do a good thorough carb cleaning but it has run for up to a about a minute. I'll post an update once I can find some time to play with it a bit.

trouts: Thank you for the link re: carb cleaning on my other thread.

Here's where I'm at with this: Cleaned and removed the carb as much as possible using carb cleaner, removed the main jet orifice and cleaned with wire and carb cleaner, dropped the float and needle and thoroughly cleaned in and around that, replaced the fuel lines, removed and cleaned the fuel tank, replaced the fuel filter. It seemed to help a bit but it will not run for more than a few seconds. Seems like once the fuel I've added to the cylinder or carb is used that's it - it dies! I really want to get this running but am getting very frustrated. Any help, suggestions, etc... are very much appreciated. borat - here's a few pic's of the carb still mounted to the engine. I can remove it again if need be, just let me know.

Did you clean the float needle and float needle seat?  Did you blow air through fuel inlet with the float needle removed? 

Sounds like fuel may not be getting into the float bowl.  It's important to follow the fuel from the tank to the float bowl.  That little screw on the bottom of float bowl is to drain the bowl.  When you remove it, does gasoline drain out?   If so, let it drain a bit into a container and confirm that it's clean fuel.  Put the screw back in.  It should start if the rest of the carb is clean. 

When you pull the jets, it's best to blow compressed air through the holes they fit in.  That will help clear the passages into the venturi.  The venturi is the throat of the carb.  Inside the venturi there may be two very small holes or possibly just one real tiny hole for the pilot jet and then a larger hole for the main jet.  It's imperative to ensure the holes and passages are clean.  If all passages, jets, orifices are clean and fuel is getting into the float bowl, the machine should run.

I just pulled the carb off of a 1965 Lawn Boy mower, cleaned it, put it back on the mower (that wasn't running) put some fuel into the tank, primed the carb  fired it up.   That's a 46 year old carb and it works great with just a thorough cleaning.  That Mikuni carb should run flawlessly if it's clean and getting fuel. 

Not really up on 2-strokes. Is there a fuel shut off,that is partially closed? Primer bulb installed correctly?
Using that so called e-85 fuel? Canot think of anything else. Hope you get it running!

T.J.

I'm going to try and get this going once and for all! I'm pretty sure the problem lies with the float and needle not allowing any fuel into the carb. I'm going to disassemble the float and needle and give it another good cleaning. When I went in there again yesterday, I found a milky looking residue coating the main jet venturi and in and around the float itself. I gave it another good spray down with carb cleaner and reassembled everything but it still will not stay running. I'm also going to recheck the fuel line from the tank to the carb and replace the fuel filter once again.

Are there any particular areas I should focus on in terms of obstructions or debris that could be restricting the flow of fuel? The machine really is in good condition and will be a nice working unit once I can get this problem resolved. Plenty of pic's to follow once I can get it operational and put back together again.

Frank,

   It could be a needle sticking problem.  I woud do what Borat sugged several times i.e. draining the bowl and letting it refill a number of times to check for the needle sticking i.e. wait long enough for refill so the needle seats.  You should get a good flow of gas everytime you open the drain. 

   As a confidence builder you can start then prime after starting and continue to prime.  If gas is making it to the bowl you should be about to force gas to the throat and keep running.

   Another thing is to put gas in a small squirt bottle,  start and feed gas in the throat which should keep it running just as a check. 

   Sometimes the fload adjust is very fussy and when I'm lost I'll adjust the tab more or less but I think on yours it may be plastic and not adjustable.    

   You've probably done this, pull the gas line from the carb and insure you get a good flow from the tank.

    Check the flow from the bowl drain.

    Run by priming.  If you can't then it's probably a float needle issue.

trouts: I have tried to use the primer to keep her running to no avail. It seems as though the primer bulb is not working to bring fuel to the carb (it's brand new as the original was missing). Any thoughts on what this may indicate or where I should focus my attention? I'm going down there now to play around with it again and will do as you and borat have suggested.

Disconnect the primer line from the carb and give the button a few punches with your finger lightly over the end of the primer line.  You should feel slight puffs of air.  If the puff is there then you have a clog in the port or insifficient gas in the bowl.   Some bulbs need a sharp push.

Is the butterfly free?  Move the lever on the top of the carb a few times.  Is the choke butterfly closing when you flip to choke?   Are you starting with choke on?

The primer should be be able to keep it going if the gas is there.  Make it run by squirting gas through the throat.

 

OK- here's some fresh photo's. If I remove the fuel line from the carb, I get a free flow of fuel. If I remove the needle from the carb, I get fuel trickling out through the hole where the needle sits. If I reinstall the float and needle, no fuel will flow out of the hole that the needle is in. See if there's anything in these photo's that might help. Does the needle look like it is in the right configuration?

Hope these help to determine what may be the problem.

trouts: I did as you suggested with the primer bulb and got that working better - I think the tube the hose slips on to was clogged. I used a spray bottle of fuel and sprayed directly into the throat and kept it running as long as I kept spraying fuel in there. I think the float and needle are the problem as fuel will flow nicely once I remove the needle. When it's installed,  I cannot seem to get any fuel to flow out of it - the needle is stopping the flow of fuel from filling the bowl. Can you tell from the pictures if the needle is installed properly? It does not seem to fit together properly unless the neck of the needle is positioned between the slot of the float - does this sound correct? What next???

   Your carb is filthy, very bad.  I'd poke all the holes with a thin wire, dip it, spray all ports with carb cleaner and air wash it. 

   The float and needle look fine.

   If I remember right, there is a screw in jet at the bottom of the center post by the plastic collar.  Unscrew it and clean it.  Run a wire up into the center tube.  Z-bend a wire and run it up in there back and forth.  Spray in there and look to see if it comes out in the throat.  It coule be your primer is not able to push gas into the throat because one of those areas is plugged. 

   "Trickle" is subjective.  The flow should be enough to replenish the bowl when you are running full speed under load. 

    I'd pull the carb and clean it, but just to get it going for now I'd clean that bottom jet and run a wire up into the emulsion tube and see if can then run.  I'd also try the squirt bottle in the carb as a confidence builder that it's not some other problem like a weird electrical problem once you get it to run.  That happened to me i.e. all the symptoms you had but it turned out that the coil wire would ground after starting.  Remote but making it run with a squirt bottle will let you know you only have a gas problem.

I don't know if the float needle is supposed to be jammed in the slot.   I've never seen that arrangement before.  I'm wondering if It should probably just rest on top of if.  Being jammed in there like that might not allow the float to drop to allow fuel into the bowl.   Generally speaking the float needle just rides on top of the float lever and some carbs have a very tiny spring clip to hold the needle on the lever so that the needle follows the float lever rather than just depending on gravity to make it drop.  Try resting the float needle between the float lever and float needle seat.  See what that does and get back to us.

Have you found a diagram for that carb?

Upon closer inspection of the pictures, it appears that the float needle arrangement might be right.  Does the needle and float move freely up and down?  If so, it's probably correct.  If it's tight and the float doesn't move at the slightest bit of pressure it might not be.  The best way to tell is to turn the carb upside down to see if the float drops with no resistance.  Turn it over to the normal position to see if it drops effortlessly.  If it doe, all is well. 

The carb is still filthy though.  You have varnish all over the place and I'd be willing to bet that the float needle seat needs to be cleaned with a wire, compressed air and a Q-tip dipped in WD-40 followed by a blast of WD-40 and more air.   Find all the tiny holes and feed a wire through them, followed by compressed air.   If the carb doesn't work, it's still dirty.

   There are some carbs where the needle just rests on the top of a float tank (not clipped to it). 

   On his carb the slot is for the needle to fit into, >>loosely<<.  The needle tang is smaller than the width of the slot.  There is a bulb end on the tang bigger than the slot to pull the needle off the seat when the gas is low.   The tang goes on the bottom side of the slot.  His looks right.

trouts and borat: Thanks for the feedback. I'll go get some Berryman's Carb Cleaner Dip and plunk the carb in there for a day or so. I was starting realize that this may be my best option as the carb cleaner spray just did not seem to do a good enough job. I'm off to the parts store (yet again) and will snap some post Berryman's photo's tomorrow.

    Get as much crud off as you can before you tank it.  Once in the basket under the solvent turn the carb with a screwdriver to get the solvent into air-locked passages.  You'll probably see a few bubbles float up.

    The solvent will not clear all crud but even the worse will usually be soft enough to break with carb spray.  So, poking with the wire, carb spraying and air wash still required. 

     Possibly you have the jet removed but in the pictures above there should be a jet at the bottom of the tube in the center of the carb.  If that was plugged it could cause what you have for a problem. 

    Poke up through the center tube inside the main tube.  

    There are holes on the right and left sides of the body which I'm not sure about.  They may be air ports but you can partly poke in there. 

    Looking into the choke side of the throat there may be holes on the right and left side about half way up.  Prod in these. 

   On the manifold side under the gasket there may be 4 holes to poke in.  You may not have those holes on your model.  My Mikuni has them. 

   On the screw head side of the low idle screw there may be two jets.  One is fixed and I think has a through hole.  I can't remember but I think that is a low speed feed limiter. 

   There should be another screw close to the top edge with a spring.  I think that controls air for high speed fuel control.  I think that one is set backed out 1 1/2 from lightly seated (It might be 1).  If it runs poorly tweak it.

The parts store I went to did not have Berryman's so I'm going to try and clean it with wires and carb cleaner. If need be, I'll go to a different store tomorrow and do the dip process. I picked up some brass and stainless steel brushes to help clean the carb and will run wires through as many holes as I can find in hopes that this finally gets the job done! I'll keep you guys posted - Thanks again for your help.

borat wrote:
The float does not move freely up and down. It almost seems like it is spring loaded in the downward position but will move up and down if I press on it without much effort. I cannot rest the needle on top of the float because there's no way it will reassemble in this configuration. I'm going to take a few more pic's with the carb removed from the engine. I just got done doing yet another carb spray, wire brush and wire cleaning so it's a lot cleaner than in the previous pictures.

I've had it for today. Here's a few more after cleaning it again.

Note how the float sits in this photo. It does not move freely but is more spring loaded (down pressure). I can move it up but the spring action forces into the position seen in this photo - even if I tip the carb upside down. Does the needle need to go in a specific way???

See how the needle is positioned - it really can't go any other way.

Looking down the throat.

One more that shows how the float is positioned.

That looks much better. 
  

Don't sweat the bit of spring tension.  It should be offset by the fuel coming into the bowl.  When the float is down like that, the fuel flows in.  As the float bowl fills, the float goes up and forces the float needle into the seat stopping fuel flow. 

Did you get a very thin wire into the holes/galleries going to the venturi and blast compressed air through them afterward?  If the jets, orifices and galleries are all as clean as the carb looks, it should work.

Keep us posted on how it goes.

The float has to be free on it's pin and not pinched on the sides.   Maybe there's varnish inside the float hinge.   Find out what's binding the float.  Pull the pin and take off the float.  The resistance had to be in the hinge area.

The spring could be in correctly or incorrectly, I forget.  Most of the Mikuni carbs I've worked on did not have springs.  Maybe the spring is in backwards.  It does not matter.  What has to happen is the tension has to be small enought that the float alone can overcome it.  You said the flow stopped when you tested that so the tension is probably ok. 

When you have it like you are holding it and the float falls to its stop it's ok.  When you tip it over the float should be level with the bowl gasket rim.  That won't happen with yours because of the spring.  You can pull the spring can check where the flot ends up when the needle seats.

Looking into the choke side there are two internal holes that can be seen in the throat that should be prodded.  

You still have the minifold and gasket on.  Those should come off before tanking.   I think there will be 4 holes in back of the gasket which must be clean and prodded.

In the prior pictures it looked like the plastic bowl stop was cracked.

Do you have the jet that screws in by the bowl stop?

Did you take out the low idle feed screw on the top of the carb and clean it and in there? 

Also, the air feed screw next to it, the black one?   Those usually are brass and have a spring on the screw.  Never saw a black one.  It looks like the type that only has a hair of adjustment.  Maybe they are like the Hondas and have to be broken to get at the screw.  ??  If you can that one should come out and be cleaned and inside cleaned.

The needle does not go in a way other than the way it must go.   The only way it will fit into the hole and slot is the way it is in the pictures.  It's fine.  But it must move freely other than the spring tension.  It should be able to go up overcomming the spring by the force of the float lift from the gas rising.  You'll have to guess that. 

What you've cleaned is external parts which is essential to stopping crud from falling off and plugging something.  What matters is the passage passageways, ports and jets to be clean like the body.  The float looked like it had varnish.  The body looked like it had prior white aluminum powder buildup with a varnish cover on top.  Both are tough to deal with in hard to reach passageways.  If not white buildup then it's probably piles caused by the oil evaporation.  Two cycle gas evaporation can be very weird and many types depending on the gas, oil used and how the buildup happened.

You can test the float action as is by dunking what you have in a class filled with water.  Does the float raise and lower properly?   You can test how soon the float lowers the needle by putting on a 1 foot section of gas line and then fill that with water.  I test needles like that all the time for seating.  Get a class with a mount that is just big enough to sit the carb body on.  Then fill the gas line (pointed up).   You should be able to fill the tube and let it sit for an hour and the level not drop any amount.

SO:

1. Insure the float is freemoving.

2. clean the jet at the bottom of the tube in the center of the carb.

3. clean emulsion tube

4. clean the ports on the manifold side.

5. clean the jets by the low idle stop screw.

6. clean the ports in the choke side of the throat.

7 prod the holes on either side of the body.

Trouts:

Sounds like you're familiar with this carb.  I've never worked on one like that, so I'm not. 

I'm wondering, that the carb might cleaned properly but the screw settings might be out of adjustment.   Does this carb have an idle screw, a pilot jet with a pilot air screw and is there any control over the main jet? 

I'm kind of doubting there will be any control over the high speed circuit (main jet) but there might be a screw to adjust the low speed circuit (pilot jet).  Usually, the pilot jet is to be fully seated then backed out anywhere from 3/4 to 1.5 turns.  It it has an idle screw, it has to be turned in enough to allow fuel air flow to keep the engine running. 

>>>I'm wondering, that the carb might cleaned properly but the screw settings might be out of adjustment.

   Could be but I doubt it because of the things below - as far as adjustments.  His does not have a nut from the bottom like a Tecumseh nut with those two holes that get plugged all the time.  His had a solid nut.  The metering hold is on the jet that screws into the base of the tube that sticks down from the center of the carb body.   He's never shown it in the pictures.  If that's plugged it's like the nut holes on a Tecumseh being plugged.  And his has others - the 4 ports on the manifold side mentioned in another post and here.  You were right twice and still right.  He's got dirt someplace(s).

Yes, it has a low idle screw just like on a Tecumseh.  That’s the one that is a physical stop to the butterfly. 

There is also the gas feed low idle jet but it’s just screwed in.  It’s not settable like on a Tecumseh.  It’s got a screw like plug that screws in.  The bottom of the plug part has a hole in it which is the low idle metering flow control hole (jet).  

There is a high main jet on the top of the carb body.  I think the way it works is the high jet controls the flow of air which controls gas flow.  His has a plastic part I’ve never seen on a Mikuni.  It’s like the plastic stops on a Honda carb jet.  At least that’s what I think it is.  It’s a plastic stop so people can’t mess with it.  On a Honda you can break off the plastic and access the slot for the screw.  On his I’m not sure.  If his is a non-removable cover then that’s a problem for cleaning access and a positive for doing a dip.  BUT, I think the 4 holes I mentioned at the back of the carb on the manifold end lead to that jet.  He can prod and squirt in through those ports. 

Chances are pretty good that there is internal varnish buildup.  Frank, remember to separate the gasket and manifold before the dip. 

well by looking at the picture of the carb sitting upside down the float is setting WAY to low (its out of adjustment by a mile), it will run lean or not at all in that postion....when the carbs upside down the float NEEDS to sit parrelle to the carb base thats VERY important.

and of course as trouts mentioned the float ABSOLUTELY MUST move freely or it will not run.

And yes the SPRING is installed backwards from what l can see.

Niper99 - it's because of that spring.  If the spring was out it should sit parallel to the bowl rim when upside down.

 install the spring so it pushs the float TOWARDS the carb

Niper99, are you sure?  I think the spring it to insure getting needle off the seat. 

nope lm 100% on this one..he could try and run it with the spring off if he wants and will should run but l suspect it could  possiably cause flooding if ran all the time with out the spring.

now that l see the carb lve work on alot of these, and some have the spring and some dont...not really sure why...but tecumseh does the exact same thing..l do know that tecumseh did it because they had flooding issuse on some of there carbs or a rich condition...(sputter)  

I've never seen a float with a spring to force it in either direction.  If I were Frank, I'd take it off just to see how things work without it.  The way the spring works in his set up is to force the float down thus ensuring the needle drops allowing fuel into the float bowl.  That will not cause a lean condition.  If anything, it might limit the ability of the float to fully close the needle.

Regardless of the float/spring issue, I'm with Trouts.  There has to be some tiny orifices and galleries plugged. 

Trouts, the hollow piece in the center that the main jet screws onto is sometimes called the diffuser.  Most of the ones I've seen have very tiny holes drilled across the tube.  As you have said, they also must be cleaned.  Personally, I think it's the orifices in the venturi that are blocked.  Nonetheless, he should pull the diffuser to ensure it's clean.  

like l said before lm not guessing lm telling u that the spring pushs the float UP not down. l have never seen a carb with a spring that pushs down EVER and l seen hundreds of carbs with springs. and l just went out to the shop and double checked my tecumseh stock with the float WITH the spring and it comes with direction on how to install float and spring...and its pushs UP.

and YES the carb will run lean or nat at all if the float is set TOO low which in the picture is how it looks, now l understand what trouts is saying if the spring is pushing it down then ya thats a problem.

but the fact is we cant tell if the float is adjusted properlly or not and in the picture looks way low, it could be the spring pushing down but that seems doubtful becuase there probally would fuel coming out of the carb all the time.  

anytime l have a no start and l want to determine if its flooding or not getting fuel is PULL THE PLUG and see if its wet or dry....its pretty hard to fix a problem without knowing those factors.

with all that said frank.. l think the thing to do is to determine if its FLOODING or NO FUEL. then we can give u a more accurate diagnoses. everybodys got there opinion and thats fine its good to see everybody helping out but it also leads u all over place, even for my self its hard to give an opinion when lm not even sure what u have or havent ruled out.

1..take pluged out blow it dry with compressed air or whatever u got just make sure its DRY.

2..crank engine over sevral times and PULL THE PLUG.

3..is it WET or DRY???

4..if its DRY then adjust your float level so the float is parallel to the carb base when upside down, and place the spring pushing UP.

5. if its WET then it could be a few different things causing it...

start with that first see what happens.

Borat:>>I've never seen a float with a spring to force it in either direction. 

 

   Tecumseh uses springs on many of their winter snowblower engines.  They often get discarded when the carb is serviced. 

 

   From the Tecumseh 4-cycle tech manual.

 

   “Some carburetors use a float dampening spring to aid the inlet valve to maintain a steady position in rough service applications. Note the position of the hooks before removing the float hinge pin (diag. 25).”

 

The Tecumseh spring has two hooks (arms) that stick out.  One rests on the carb body hinge area.  The other goes to the back of the float.  The Tecumseh spring is very weak and won’t push up or down.  It just provides a slight force to the float and hinge I think to reduce float bouncing on the hinge pin. See: http://outdoorpowerinfo.com/repairs/tecumseh_carb_damping_spring.asp

 

     When I get one like this I usually have to muck with it to get it right.  If I remember right one way will make it not work and the other work.  In the wrong direction the spring it too much force to overcome to make the float work properly.  I’ve got three Mikunis here and none have springs (probably lost before got them).   Put it in a class of water with the bowl off and verify how it works with the current spring setting. 

 

Borat>>>Trouts, the hollow piece in the center that the main jet screws onto is sometimes called the diffuser.  Nonetheless, he should pull the diffuser to ensure it's clean. 

 

    Sometimes they are referenced as emulsion tubes and other places diffusers.  On a Tecumseh they are just a straight tube.  I never replace them, only run a wire through.  As a note: the local Honda/Snapper dealer replaces that tube on every carb rebuild.  I’ve never had a problem leaving them in and only cleaning them but that’s only on Tecumseh winter carbs which is what I mostly work on.

 

   A Mikuni is more complex with the series of holes which can draw more or less fuel with increased throttle settings.  They have to be clean.  Normally I would not pull the tube but given the amount of crud in his carb I would.

 

   He has not mentioned a starting problem which he’d have if he was flooding.  I have had carbs that acted like his.  They would wet the plug right after starting but then not start which he had not mentioned.  Whatever, pulling the plug is always a worthwhile check.

    Getting the spring right is easy enough.  The carb is still dirty and needs cleaning.

Here's some photo's of the carb partially disassembled. The little spring seems to do nothing more than secure the hinge pin to the float. It makes no difference if it is removed or not as the float still has that spring loaded feel regardless if it's attached or not.

Needle, hinge pin and spring.

Side shot with all of the above removed.

Front shot of same.

Side shot of the whole carb with spring attached (not that it makes a difference).

I did remove and clean the main jet inside the tube that goes through the center of the float. I cannot remove the black plastic piece at the bottom of that tube so I cannot completely remove the float. I don't want to force it and possibly break it. I read on a can of "Gunk" brand carb cleaner dip that all plastic must be removed before placing carb in the can. I think I need to dip this to get inside all the tiny orifices but do not want to risk ruining the plastic parts that I can't remove Any thoughts? For nothing else, I'm getting very good at removing the carb and feeling much more comfortable doing so.

Frank i have a big concern with how the float is sitting way to low. that just doesnt seem right...Frank did u remove the needle and SEAT?..if so is the SEAT pushed in ALL the way. l just dont see how this carb is gonna work as long as that float is sitting that LOW...the fuel not even gonna be able the reach the emolsion tube (main jet).

And l agree with trouts and borat that it is most likely a lean condition.. l was simply pointing out how l the spring was installed and how to go about finding out if its lean or rich. and how l feel it works. but to make it simple just dont use the spring for now..at least until u get running...it will NOT effect the starting of the engine.

and frank when l say the floats sitting LOW l mean high when your looking at the carb is upside down. l also noticed by looking at the pics that this float doesnt look adjustable??.

frank when u say IT STILL HAS A SPRINGIE FEEL with the spring removed..push down on the float and look closely to see if the float is FLEXING or is the needle MOVING down and seating properely. u need to determine this before going any further in my opinion.  If its FLEXING make the SEAT in pushed in all the way.

trouts: It will start and stay running as long as I continue to spray fuel into the throat. If I stop spraying fuel she dies. I really don't see any small holes to clean with a wire so I'm leaning towards getting a dip type carb cleaner but I am worried about the plastic eroding. Is it OK to dip the carb with the plastic parts attached? I cannot remove the plastic float unless I remove the plastic black collar - any suggestions?

nipper99: I pressed the needle down into the seat as you suggested and it did make a difference. The float now sits off of the black plastic collar about 3/16" if I tip it upside down. Before it was pressed up against the black collar with spring loaded tension. Now it will move freely if I tip it upside down/right side up. Again, I think I need to dip this to help give it a good cleaning - is there a carb cleaning dip that won't erode the plastic or is there a trick to removing that black plastic collar? 

frank l think we may have made some progress:) if u pushed the float down and theres more play thats a good thing...now is the float adjustable or was the seat loose? u gonna need to get a drill bit thats a little bit smaller than the seat and push on the seat with some GOOD pressure to make sure its seated all the way in. and u need to know if your floats adjustable?? post a pic of the float and i can tell u. just curious after u push on the needle and seat did u run it?

alot of carb cleaning products usually dont like plastic parts....but u NEED to get the float figured out first then if it still wont run then think about soaking the carb.

Frank:

I doubt that just soaking the carb will get the job done.

Get a magnifying glass and look into the bottom of the throat of the carb.  There will be very tiny holes there that are difficult to see.  They are so small that you need to use a trash bag tie wrap with the covering stripped off of it to fit in the hole.  That's how small they are.   What I do when I find the hole is make a 90 degree bend in the wire with about 1/8" bent.  Line it up with the orifice and try to push it in with your finger.  Once you get the wire in, try to feed more wire into the hole.  Usually, the wire will end up feeding all the way to the pilot jet hole.  Once you get it there, if you do, flush with WD-40/carb cleaner and blow compressed air into the pilot jet hole.   You should see fluid blow through the tiny orifice in the throat of the carb.  When you do, it will be clean. 

Niper is on the right track regarding the float.  I'm not familiar with that carb but proper float setting is imperative.   Follow his guidance and get the float set right. 
Did you ever find a diagram for the carb and correct float setting info?

You can test the float effectiveness by leaving the float bowl off and connect a length of hose to the fuel inlet.  With the carb in the upright position, lift the float to seat the float needle.  Pour water into the hose.  It should not flow through until you lower the float allowing the float needle to unseat.   If the engine is starving for fuel, it appears that the float situation is the source of the problem.  

Good luck and keep at it. 

Borat,

  There is no tang on the float to adjust.

 Frank>>>It will start and stay running as long as I continue to spray fuel into the throat. If I stop spraying fuel she dies.

OK, you’ve only got a simple problem.

Frank>>>I really don't see any small holes to clean with a wire

Read above again.  There has to be openings in the throat or the carb could not function.  Also, did you take off the black manifold and gasket?  There should be ports there, probably four.

Frank>>>I cannot remove the plastic float unless I remove the plastic black collar - any suggestions?

Hit it with carb spray and keep lightly tapping it.  It’s stuck to the center tube with varnish.  Worse case is break it and get another.  If you can take out the emulsion tube you can probably bypass the dip, get the thing running and on a second pass break off the collar and order another.  A local dealer may have one.

You’ve never responded about the jet that fits on the bottom of the tube sticking down from the center of the carb. In the first picture of post 49 the jet is not there.  Do you have that jet?

Frank>>>I pressed the needle down into the seat as you suggested and it did make a difference.

The needle has to be able to move on the float.  It’s a slot and if you insert it with the needle at too far in one direction the needle will not go in properly.  It’s has to be somewhat free in that slot so it can seat properly.

Niper99,

I’ve never seen a spring of that type in a Mikuni.  What I usually see is an elongated U shaped spring with loops on each end that fit on the rod that holds the float on.  ??

Niper99>>>u need to know if your floats adjustable

His is not adjustable.  There is not flexible float tang to move.  There is only the slots into which the needle slides.  The needle is put into the slot and the float pushed up so the needle goes fully into the seat.  If the needle is too far back or forward in the slot it won’t go in properly. 

Frank,  It just occured to me that if you have not taken off the float you have not cleaned and inspected the needle seat area.  Work the collar off to get the float out so you can see what's going on with the needle.

thanks trouts for the info on the float ADJUSTABILITY....ya as trouts mentioned the float and needle MUST come out for inspection and cleaning at the MINIMUM, l didnt realize u havent removed the float yet. take long needle nose pliers or whatever will work and put them under the black bracket hit the pliers with the hammer it should come off... thats how lve removed them in the past..dont be afraid of giving it a good little wack..put the carb in a vise first or have someone help hold it while u tap it off (a vise is MUCH easier).

at this piont l personally would scrap the needle and float and install a new ones...by the sounds of it the needle and float arnt working properlly together (moving freely)...and as trouts has pointed out the float is NOT ADJUSTABLE so with that said the problem lies within the float and needle, and as long as thats happening then your going to have problems...so for peace of mind l would without a doubt replace the needle and float...and most likely the seat is a press in brass seat which u should be fine leaving in, but clean very good in there (spray carb cleaner in there) and as borat and trouts have already mentioned give the carb a good cleaning.....lm confindent with cleaning and replacement of the float and needle that should get u running!

   The float is ok, not broken or leaking.  It's static, a molded piece and as long as it's not broken or leaking it's fine. 

    The needle is probably fine also.  The only thing he needs may be a seat but ht has not been flooding just starved and a cleaning in there will probably take care of things.  He's checked the flow and gets gas out of the drain but that may be a restricted flow.  The emuslion tube was not cleaned before and now is so cleaning the needle and seat area should help along with taking the manifold and gasket off and cleaning that area also.  The manifold area (back of the carb) could be causing all the problems so should be cleaned.

   The only other thing is the spring which can be left off (I have three Mikuni's here with no spring) or leave the spring in.  If confused about the spring orientation then put the carb in a class of water.  It can only go in 1 of two ways so the check easy. 

   Another point for no needle, seat and float is the needle and seat kit is about $18 and the float $18.

  

If  the issue is not getting fuel into the float bowl, there must be an obstruction in the float seat.   With the float in the down position, the needle must follow and fuel should flow.   Performing the above test with a piece of hose and water will confirm the float and needle effectiveness.  If he get's good flow into the float bowl, the only thing left is obstruction in the venturi orifices, main/pilot jet and/or gallery obstruction, emulsion tube obstruction. 

 I wish I had that carb in my hands.  I really enjoy working on carbs.    

To a person with limited carburetor maintenance experience such as Frank, there is a huge learning curve.  Hats off for him having the ambition and courage to roll up his sleeves and get at it. 

I'm  waiting for a replacement reed plate and carb for one of the old Lawn Boys I recently bought.  When I get the reed plate, I plan on experimenting with a suitably sized carburetor off of a 1964 Mercury 3.9 h.p. outboard motor.   I want to see if it will fit and work on the mower.   

I had an initial brain wave to put the power head from the outboard  on the mower.  Then the liquid cooling issue arose which would require a a radiator and a pump etc.....   Not going to happen.  The carb experiment will have to do.

Below are the ports on the manifold side of a Mikuni.  The collar on this one was stuck like most but comes right off with light tapping.  The tab on the collar prevents the float from going too low which would allow the needle to fall out.

That is one grimy carb Trouts. 

Looks like it's been subjected to a fair amount of corrosion probably from salt.  That baby has to come completely apart including the butterfly valve if you can get it out without breaking the little screw that's holding it in.  It looks pretty rusted.   

the fuel level in the carb must sit high enough that the emolsion tube sits in the fuel.. if not it will not run.

lm worried that the float is pinching the needle to tight and its not moving freely....or maybe its just full of junk where the needle and seat is?.

now IF the float was moving freely the engine would run on full throttle only..EVEN if every other orfices was plugged in the carb.....and we know that becase when frank sprays fuel into the throat of the carb its stays running....so if the MAIN JET isnt plugged (which frank says its clean) then that would CONFIRM that the fuel level in the carb isnt correct...and the only thing that controls fuel level is the the FLOAT & NEEDLE opeartion.

"then that would CONFIRM that the fuel level in the carb isnt correct...and the only thing that controls fuel level is the the FLOAT & NEEDLE opeartion."

Makes sense. 

That's why he should do a test with a piece of hose full of water attached to the fuel inlet to see if the float is operating correctly.   With the very slightest amount of upward pressure, it should seat the float needle.  Release the float and it should just drop allowing the water to flow down past the float needle. 

I agree that the engine should run at speed off of just the main jet.  If he can get the engine to run by injecting fuel into the venturi, and it doesn't run on it's own, there's probably no fuel in the float bowl. 

Got to wonder what's going on with this carb.  From the pictures, it looks like it should go.  However, we have not seen the needle seat. 

trouts, borat, nipper: I can't thank you guys enough for your guidance and insight with this project. The beers are on me when we finally get this finished! 

I had a busy day so I was not able to spend too much time on this today but here's where I'm at so far. I was able to remove (and not damage) the black plastic collar on the main jet tube - it was pretty nasty under there. I then removed the float and gave both areas a thorough cleaning. Pressed the seat inside where the needle sits but I think it needs to be replaced as it did not make too much of a difference from the first time I pressed it inward. The float when reinstalled still does not sit level no matter how much or hard I try to press the needle inward.

I also removed the black chunky gasket type component on the manifold end and was finally able to see and access the 3 mysterious holes that were eluding me. I gave them all a good dose of the bag tie wire and hosed everything down with copious amounts of carb cleaner. I reinstalled everything and got ready to fire her up!

Unfortunately, she would only stay running as long as I kept spraying fuel directly into the throat. VERY frustrating!!!! I can keep her going indefinitely if I'm spraying fuel in the throat.

What do you guys think - replace the needle seat and see what that does? I lost the little spring but as trouts stated and I agree, I don't think it makes much of a difference. The float seems to be restricted in terms of movement. It does not have a whole lot of free play and still feels kind of spring loaded which is why I'm thinking I should replace the seat and see what that does. To be honest, I'm almost thinking of replacing the carb completely but I've gone this far so replacing a few parts in hopes of getting this resolved is an acceptable option. I'd like to keep it original if at all possible.

On the bright side, we've got about another 7 months or so to get this problem resolved and I've gained a ton of experience!

Once again, I thank you guys for all your help.

Frank

if it was me frank l would replace the needle & seat and float just for peace of mind at this point.

What is the factory model number of your machine?  

When put back together, drain through the bowl to see if you get a decent flow.

You can keep it running by squirting in gas but can you now prime it to keep it running?

You should be able to prime many times and get gas in the throat.  If not and you have no air leaks which you don't then something is fuzzy in the needle area.

Is there a jet at the base of the center tube by the cutout part of the black collar?  It would be a small screw-in part.  That should be there and very clean.

I would verify float operation in a glass before I bought anything.   Also in the sink, put a small length of gas line on and fill the line with water when the blow is held up with your finger.  It should hold the water and when you drop the bowl flow freely.  Does that flow look about that you get when you drain with the gas drain on the bottom of the carb bowl?  It should be close.  You should be able to lift the carb up to let the float drop and get flow.  After putting the carb back into the water flow should stop.  The needle should never stick and what you want to look for.

When sitting in the glass on the glass rim you should be able to leave it for an hour with no leak. 

trouts: Model number is 38430, s/n  is 7908851. This indicates a 1997 date of manufacture.

The prmer bulb works mechanically, but will not provide fuel to the carb as it should. It is brand new as the original was missing so I bought and installed a new one. Not sure why the primer does not work as it should. The engine will stay running as long as I continue to spray fuel directly into the carb throat.

Look at the previously posted pictures of the carb tube base - I do not see any type of jet on or near the black plastic collar. The only one is located inside the tube and can be remove by backing it out like a screw. That is very clean and the orifices are open.

I'm going to replace the needle, needle seat and float as suggested by nipper and see if that cures the problem. It seems as though the fuel cannot get past these areas to feed the carb and keep her running. It's hard to see into the needle seat but it looks like the rubber is damaged in one area which may be causing the fuel feed problems. I assume that the cost of these parts is much less expensive than replacing the whole carb (+/- $100.00) so I'll take a chance and see what happens.

Question - how do I remove the seat without damaging the carb? It appears to be made of brass and rubber and is pressed into the hole where it belongs. Do I try and grap it with needle nose pliers or use a screw inserted into the opening and pull it out that way? Just not sure what is the best way to remove this so I can replace it.

Any other suggestions or thoughts are very welcome.

"The prmer bulb works mechanically, but will not provide fuel to the carb as it should." That's an awful big coincidence. Too big. I would find out why that's not working before doing anything else, it could very well be another symptom of why your carb isn't getting fuel.

FrankMA wrote:

Frank......in regards to the SEAT...if its brass then l usually never replace them...of course if looks damaged then yes l would replace it... if not just leave in...most important is the NEEDLE & FLOAT get replaced.....and make sure its VERY clean where the needle moves up and down spray carb cleaner in there and use a pick or small screwdriver with a rag and give a good clean just be careful not the scratch the carb.

as for the primer it will not squirt fuel in the carb if theres no fuel in the bowl. 

Well I downloaded the parts manual which has a great blow up and breakdown of the entire carb assembly. Called my local dealer and here's what the replacement costs are for the following:

Complete Carb Assembly..............................$ 163.34 (YIKES!!!)

Carb Rebuild Kit..............................................$  68.74

Needle Valve Seat Kit....................................$  28.64   DING...DING...DING - we have a winner here!

I'm pretty sure it's the o-ring inside the seat thats either all gummed up or damaged. It's very hard to see inside the seat area but from what I can see, the o-ring appears to be damaged or torn somehow. The parts guy said it can be removed by using a dental type pick or applying compressed air to the fuel inlet which will force out the seat. At any rate, I'm going to give this a shot and see if this solves the problem. This area seems to be the bottle neck in terms of fuel distribution so I'm confident that this may do the trick. I going to try and get to this in the next day or so and will keep you posted. Hopefully this will resolve the problem and I can get this operational and still be well under $100.00 for this gem.

FrankMA wrote:
Yowser!!!  If these prices are for Toro, I think parts for my Honda is pretty cheap in comparison.

I hope those at least includes assembly and warranty. 

No wonder why people go to big box stores and buy disposable OPE these days.

Sad thing is, there are people who would pay that much to get it fixed.

Sad thing is, there are people who gives away their snowblower to the local dealer.  That dealer puts in $50 worth of parts and labor to get it running, turns around and sell used for $300.

Sad thing is, there are people who think they're pretty smart for doing that. 

Sometimes ignorance is bliss, most of the time, it's going to cost you.  That's why it's always good to know just a little bit to be dangerous. 


Anyways, hope you get that machine fixed up ready to run for next winter.  It's good to see the progression of the troubleshooting and solutions.

You’re going with replacing parts which could work.  It looks like the parts are fine but just taking things apart and putting them back could cure things.  I don’t think they will make a difference. 

 

For reference:

From what’s been posted it seems the block is behind the seat in the area between the seat and the fuel inlet.  Replacing the float and needle won’t affect those.  Removing the seat would.  But that’s a possible problem. 

 

The reason is dealing with the brass insert.

 

On your model the factory puts in the seat and then puts in the brass insert.  The seat shape is a small doughnut over a large doughnut.  The large doughnut part is the size of the needle hole which is also the size of the brass insert OD.  The smaller doughnut is the size of the brass part ID. 

The seat goes in then the brass insert.  The insert covers and holds down the seat large part of the seat.  The smaller part ends up inside the insert. 

 

When you look into the carb needle hole what you see is the brass insert and the small part of the seat. You do not see the full seat which is under the brass insert holding it down.  Removing the seat requires a carb tool with a crochet end.  Using a small probe like can be used for a Tecumseh seat won’t work without damaging the seat.  If you could get it out you can’t insert a new seat as it’s too large without first removing the brass insert. 

 

Removing the brass insert can be a problem.  There’s no lip at the bottom to get a grip on with the carb tool.  Some ways to get the insert out are screw in a screw and pull or tap it put in a machine screw and pull it out or just drill it out.

 

All in all it would be much easier to clear the block behind the seat.  You mentioned the seat may be damaged and if so you have to deal with the brass insert.  If it’s not damaged then you don’t need anything other than to probe and clean the area behind the seat to the carb inlet.

  Just read your update after I posted the above.

  The seats of some carbs can be blown out but I don't think this type of double doghnut with the brass insert could work. 

   I have a few dental tools which are like the Briggs carb tool.  The difference is they have a much sharper point than the blunted carb tool and sometimes rip seats where the carb tool does not.  The Mikuni double doghnut seat is really in there and very difficult to get out without dammaging it - even damaging it without a carb tool because of it being held inplace by the brass insert.

   Not a big deal if your seat is not dammaged as all you need is to clean. 

  

Two kits sold for part 81-5820 which superceeds 81-4700.  So two different needle styles and on kit with no insert but both 81-5820's.

Frank, as a note the jet (main jet) at the bottom of the center carb tube is what I have always seen in the Mukini carbs I've worked on.  It turns out the main jet was moved to the bottom of the emulsion tube in the center of the main tube on your carb.  The hole on your carb is just a hole and smaller than most Mikuni's which fit the main jet. 

The needles on Mikuni's I've replaced have all been rubber tipped needles.  I've never had to pull a rubber seat as they were always good in the carbs I've cleaned.  They are more rugged rubber than in Tecumseh carbs. 

Because of this thread I checked out the carb I posted a picture of above.  It has (had) the rubber seat and brass insert.  With difficulty I did manage to get the seat out with the Briggs carb tool.  I could not get the brass insert out after a few attempts so left it.  I could not get the rubber seat back in after great effort.   I think the only way to get it back in is by removing the insert.  There too much meat to press it back in.  I could not even get it in the hole.  If it could be forced in the chances of it seating the lower lip of the seat is probably impossible.  So, the only way to deal with this carb that I can see is to remove the insert for a seat swap.

I'll take another good look at it later today and see if I can determine exactly what the problem might be. It does not sound or look like it's an easy job to remove the brass insert. Perhaps a chunk of garbage from the old stale fuel is lodged inside there and causing a restriction. It's just so hard to look inside there from either the needle side or the fuel inlet tube.

wow thats a bit pricey for parts.....ok lets take a closer look at the needle and float and how they go together...lm sure the problem is there....when u turn the carb upside the float should drop and sit level with no resistance...then if u turn the carb upright it should drop and sit on the black callaur with no resistance... if thats not happening then your gonna need to figure out why....

first reason l would think is theres dirt and grude in where the needle and seat are... 2 the needle isnt moving freely on the float (the plastic where the needle goes in is pinching the needle to tight) those are the only things l can think it would be.

at this point l wouldnt be to worried about the seat because if that was the problem it most likely would be flooding the engine, not stoping fuel from entering....of cousre make sure its clean at run some water through it to confirm u should easily be able to rule that out.

trouts2 wrote:

trouts and frank

in regards to removing a brass seat....what l usually do is take my tap and die set and tap the brass seat (to whatever size of bolt that will fit) ... then get a bolt and thread it in, put a nut on the bolt first then tighten the bolt up and then tighten the nut up and it usually comes right out. sometimes u need to jig something up to make a space between the seat and nut. l also have a little tiny slide hammer that l sometimes attach to the bolt to remove the seat.....but to be honest l RARELY replace brass seats.

Niper99>>>"slide hammer" - - I like that. OK on tapping.  Probably the over all safest and easiest. 

In the past I was confused about this type of seat.  Looking in there I did not see the usual Tecumseh style of seat I'm used to.  It looked like metal in there almost like the seat was removed and it was a metal to metal fit between the seat and needle or even someone had goofed up and put a metal tipped needle in there inplace of a rubber tipped needle. 

I did get the rubber seat out with the Briggs tool but it was a struggle.  I'll tap it to get the seat out.  Picked up a 40 piece metric tap set the other day for $11.   It paid for itself already on a broken bolt. 

Frank,

   It is possible to get a good view in there to insure you have the needle area clean.  If you shine a flashlight in there with a magnifing glass the area can be viewed.  The brass wall makes a clean 90 with the seat which is flat and has a sharp edged hole in the center.  Normally you'd expect a bevel on the hole but looks like a 90 unless a very minute bevel.   Your's is probably not damaged being well protected by crud. 

I've never had a carb yet that had to have the float needle seat replaced or repaired.   Usually, the float needle would be the source of the problem and even that's a rarity.   Sometimes the float needle would corrode slightly and develop a bit of pitting or a faint recession in the area where it would seat.   Even on 40 year old carburetors it was rare to anything but clean the needle and seat. 

This problem that Frank is having is perplexing to say the least. 

A bit of measurable success to report! I took apart the float and needle and poked and prodded with a paper clip, dental pick and pressed into the seat using an 8 penny nail head (seemed to be about the right size). Hosed it all down from both directions (needle and fuel inlet sides) and reassembled the whole enchilada. I removed the drain screw to ensure a flow of fuel into the bowl (eureka!) and fired her up.

She ran without any assistance from me (i.e. spraying fuel into the throat) for close to a minute. I fired her up again and she ran up and down, high revs then slower revs, kind of elliptical in sound with the higher revs being more prominent. I could get it to even out a bit by gently and sparingly using the primer bulb to feed fuel into the throat. I can't get it to even out and run smoothly unless I use the primer.

This is the most headway I've made in quite some time and feel like a real fix is just within reach -  I needed a little bit of encouragement at this stage of the game. I'm leaning towards the carb being starved of fuel a bit and perhaps a little more attention to the needle seat is required? Any suggestions on where to go from here?

   Congradulations, you're just about there.  What you've described is very good and what I get when I miss some specs.  The varnish in the photos looked lumpy in spots and a brown coating in others which is tough to fully remove from areas you can't directly poke.  More of the same cleaning should get it. 

   It could be the float is off but more likely just some spec's somewhere.   Drain the bowl and check for specs.  If there are then may be just dumping those will work.  

   What did you set the top screw to?  I think it's 1 or 1 1/2 out from gently closed.  You could try backing that out to 2 and see what happens.  If it needs more than that something is wrong.  Actually 2 would indicate somethings wrong but you'd be very close.

  If no specs or the needle adjust does not work then another round of cleaning.  Make sure you have a good flow from the bowl drain.   Focus on the main jet and emulsion tube.  Be gently in the seat area.

ALSO.... Sometimes it takes a few minutes of warmup for it to run smooth but if you're getting wide throbbing then likely dirt.  It could clear by itself with several minutes of running.

Top screw - is that the one with the spring around the threads? I made some adjustments with that one just now and it did not seem to make a difference. The engine sounds like it's hunting - revs up then down, up then down. I can smooth it out agian by gently and sparingly using the primer bulb. I almost hate to mess with the needle seat again. What do you think?

Sounds like restricted fuel flow into the main jet.  As Trouts says, pull the carb, inspect for dirt, pull the main jet and emulsion tube and clean again.  You'd be wise to put a small in line fuel filter between tank and carb.   You should clean the float needle seat some more and blow through it with compressed air.   Eliminating dirt from the fuel and carb is essential. 

I've replace the fuel filter twice. The main jet and nozzle are clean and good to go. I'll get into the needle seat area and give it the once over again.

Let this be a lesson to those who let their carbs go to hell in a hand basket - keep your carb clean and your fuel fresh!!!

I keep seeing pictures of this float thinking  it's installed upside-Down... Does anyone else see this problem?

Friiy

friiy wrote:
Doesn't look like it would fit any other way.  If reversed, it would conflict with the black plastic collar and I doubt that it would be able to move through it's arc. 

Please try it it for me...  This post is too long too read...   :(

Troll-Friiy

Maybe I am wrong...IT just doen't look right..

Friiy

For the amount of time we've been trying to get this carb working, I probably could have built him one. 

Speaking of carbs, I'm working on a Lawn Boy 7050 with a plastic carb.   I bought it used and it appears that previous owners had jacked it around a bit.  Carb governor parts were missing and someone had the throttle governor wired wide open.  Mower needs some parts but the engine is very sound and fairly fresh.  Lots of compression and it looks virtually new. 

Should be a good runner once I get if fired up.

That float can fit no other way than the way it is. I cleaned everything once again and now the fuel to the bowl is restricied again. I'll have to disassemble it and find the sweet spot for the needle - I thought I noticed a spot when I was rotating the needle that seemed to find itself a home. I'm sure there's a sweet spot for everything as this machine was built back in 1997. Too late for tonite so I'll try yet again tomorrow. Thanks as always for your help.

FrankMA wrote:

well some progress is better than none:)....ok l got a few questions for ya...

1: u need to pull the carb off again and remove bowl..and turn it upside down does the float sit LEVEL yes or no??

2: turn the carb upside right..does the float move down without any resistance and sit on the black collaur YES or NO??

3: repeat the above 3 or 4 times.. and make sure to note if 1 and 2 are happening consistently??

4: when u ran the engine today and u said it ran for about a minute...did it DIE on its own or did u turn it off??

5: if the FLOAT is NOT moving freely and consistently and wont sit in the LEVEL postion consistently then u need to replace them NO MATTER THE PRICE. because they are not operating proberly for whatever the reason.

Frank just in your last post alone tells me theres something wrong with the NEEDLE or SEAT or FLOAT...or the combination of the three....with that said u NEED to rule which one it is....now in my opinion i doubt its the SEAT...why because seat problems rarely cause no fuel to enter the carb USUALLY they mostly cause flooding..so if u do the above TEST it WILL tell u whats wrong. and there NO sweet spot to put the needle in.. if thats the case u need to replace parts. also doing the above test will rule out any DIRT getting in there and jamming needle up in the cavity. 

if the main jet is clean and u have the correct float level then the engine WILL run at full throttle WITHOUT surging.

without eliminating the carbs functions that are suspectingly at failure then were just going around in circles.

Friiy,

  Good observation Friiy,  a reversed float would jamb the needle into the seat more and have a very limited flow in if any gas.  He's got the float right, bevel up in the direction of the body.

Just for reference: A better picture of the double doghnut seat.  The bowl nut with no holes like in a Tecumseh nut.  Inlet jet on the left which on my Mikuni goes into the bottom of the tube extending from the center of the carb body.  On his the jet is screwed into the bottom of the emusion/diffusion tube.   Three Miduni needles.  His is the top, no rubber tip as his has the double doghnut seat.

Borat,

   I don't get bad seats that often but do get them.  They are sometimes worn or overly stiff with age.  Some cause the needle to stick and not unseat easily.  It's a pain to go through a carb and have a problem after installing it.  I've gotten to the point that on any Tecumseh carb rebuild or clean I put in a new seat.  It's the same for needles.  It's very rare to get a worn metal needle but I have seen a few.  I can't find a source of seats only so have to buy kits which come with needles so always replace them also (on Tecumseh's).

   Tried a little harder at getting a veiw inside a needle area.  The photo on the left is a neelde area of a Mikuni like his which has a double doghnut seat, now removed.  On the right is a Mikuni from a Powerlite.  It looks similar but does not use a rubber seat.  It uses rubber tipped needle. 

  

Good info Trouts. 

Hopefully, Frank will have this straightened out before the snow flies. 

I'm working on three old Lawn Boy mowers I picked up cheap.  Need some parts on a couple and have found a great source.  Looking forward to getting all three of them operating.

trouts2 wrote:
hey trouts...does your float and needle move freely as it would normally??....just wondering if yes how much play is there where the needle inserts between the plastic float?...l assume it should move freely with NO resistance. so if u were to install the needle in the float and u turn the float on its side the needle should just fall out on its own...does this happen?? if YES frank should do the same test to see if his float is pinching the needle to tight causing it to jam.

Niper99,

    The needle goes in its slot without resistance.  It flops around when upright in the slot.  It should not stay in position when tipped.  It should fall out, no resistance.  The needle mid section is smaller than the needle hole.  It can move in there but the movement is tiny.  The loose needle will always lign up with the seat hole.

 

I've gained a ton of experience from this project which is what I wanted, however I feel like this is going on far too long and would like to put this to rest.

What course of action do you think I should take??? Replace the o-rings and needle? I can probably remove the brass insert with a tap and die set in order to replace the o-rings. The float seems to be OK so I'd rule that out as a source of the problem. Where should I go from here?

The overall condition of the machine is excellent and I'd really like to get this operational for next season. I appreciate your suggestions.

Send the carb to Trouts if he's interested.  You two guys aren't all that far apart right. 

I'd like to fix it myself but being in Canada.........

borat wrote:
I travel through Marlboro quite often and have thought about paying him a visit.... What kind of beverage do you prefer Mr. Trouts2???

trouts2 wrote:

frank lm curious if your needle and float do the same as trouts?? read above

niper99 wrote:
Yes - the needle sits loosely inside the seat area. When I mentioned a "sweet spot", I took the needle and kind of rotated around while it was inside the seat. It seemed as though there was one spot that the needle sort of favored. Maybe it just seemed that way to me, but the funny part was that it got the carb working. I did not have time to mess with it last night so I cannot prove if this is relevant. It's starting to get a bit old at this point.

You could bring the machine here if you want.  I could go through the carb and try firing it up while you’re here.  If it’s still putzed up I’d dip it overnight.  I’m one mile and one turn off 495 exit 24A.  If you want to do that email me, trouts2@gmail.com. 

The needle should just fall into the needle hole from any 360 position above the hole.  The insert wall should be very clean like the carb on the right in post #92 and no crud or burs on the needle body.  It should not stick or catch in any way.  There should not be any sort of sweet spot for the needle as it’s all symmetrical in there.   

I'm going to try a bit more to get this resolved. Maybe another good cleaning in and around the seat will get her fixed. I'll replace the needle and seat if this does not work and will take you up on your offer trouts, if I still cannot get this running correctly. There has to be an obstruction in the seat area that's creating this problem. I'll try to get to it again in the next day or so and will advise.

    I'd get a strong light and magnifying glass peep into the needle area.  Taking a picture is easier if your camera can focus close.  On high res you can back away a bit and then blowup the image on the computer.  The area should be very clean. 

    In back of the seat you can only deal with poking and flushing.  

    Worse case bring the machine over and we'll take a look at "the carburetor that ate Cleveland". 

So, just a recap...  The unit runs, but still surges under no load ?

Are you sure the upper fixed jet is clear ?  (The one that screws down in on the top to the carb) ------  sorry, just have to ask...

Most people don't realize that the jet has a small metered hole on the bottom that intersects with the main hole that is drilled straight through....

It may be that some shop has replaced this metered jet  in the last 14 years with something they had "laying around" out of another carb.... (a smaller leaner jet)

....Or drill the hole out one size larger with a small wire gauge drill bit, going just  one size larger then what  will currently fit..

You may want to try as a option,  taking that jet  and file it out with a "torch tip cleaner",  making that jet larger for more fuel flow at low speed when the engine is surging..

You have spent a lot of time on this unit already, It is about time to try something new.....(we all like to work on stuff,  But I would kill myself if I spent 2 weeks of my life working on it with no results)

Good Luck,

Friiy

P.S. like these....http://www.google.com/products/catalog?q=torch+tip+cleaner&rls=com.microsoft:en-us:IE-Address&oe=UTF-8&um=1&ie=UTF-8&cid=12703130376543052729&sa=X&ei=rw2yTYfJAaTL0QHEoZWKCQ&ved=0CC0Q8wIwAA#

Well Frank....at this point l think its safe to say the float is GOOD...so this only leaves the needle and seat being an issuse.. with that said l would tear down the carb and soak it for at least 24hrs then your safe in that department...and REPALCE the needle and seat and hope for the best thats all u can do, either its gonna work or not and if not try and get a used carb thats in good shape..and maybe trouts can build u one (of course if he has one that will work) then ship it to u and that might save u a few bucks just thought.

anyways hope u get r running good luck!

OK, I can get it running without stalling but it is still surging. I can get it to run pretty smoothly if I gently pump the primer bulb. I tried to adjust the pilot screw (the one with the spring running through the center of it - p/n 50-2360) but that did not seem to do anything either way. I turned it all the way in, then backed it off about 2 - 2.5 turns but again, it did not make any difference. What to try next?

frank where u able to SOAK the carb?

well its diffently running lean....the adjustment screw is for the idle circuit which u need to adjust at an idle...will the engine idle at all?

does the engine surge at idle or full throttle?.....either way frank the carbs certianly sounds like its dirty still and will require a SOAK....although with soaking the carb it will require u removing the rubber SEAT and all plastics.

niper99 wrote:
niper: I did not soak the carb yet. The engine will idle but it still surges. I put the engine under load by engaging the impeller and it still surges. I think it would have stalled if I did not keep pressing the primer bulb. I'm kind of hoping that if I let it idle for a bit, it might just clear itself out (wishful thinking!).

Frank, if you do dip it, wich is what I would do next, turn it around a few times slowly when it in the basket in the can.  The idea being to get as much as possible in all passages.  Take out both jets from the outside top and make sure they are in good shape.

Those do hunt and have to be very clean.  They are pretty stubborn.  Some will hunt for a few minutes before they clear.  Others will have a slight hunt which clears when fully loaded clearing snow.  

If running with a slight hunt at full speed but cleared under snow loading I'd live with it.  But you don't have a way to load it.

The engine is still running at LOW throttle when the engine is turning the auger/ driving the unit ( not throwing snow). If you look at the throttle shaft difference between idle and running/ turning auger and drive. The throttle shaft only opens or turns a fraction of it's full travel... Meaning all your woes are in the low speed circuit of the carb, Not in the float Assy or needle. If you had a needle / float issue, the carb would flood all over your floor half of the time, meaning if a carb float sticks closed---not giving the bowl fuel,, it sticks open. -- "flooding"--- just as much. It can't be only be one way or the other. This carb should have 2 or 3 small holes next to the throttle butterfly on the side of the throat of the carb. These holes should be have spray flowing through them if you spray cleaner into the hole of the adjustment jet (the one with the spring). Also you should be able to see spray coming from carb bowl tower ( The post that sticks through the hole of the float and has the bowl nut on the bottom), and through the low speed jet hole. ( The slotted screw jet that screws vertically from the top) The low speed jet is changeable ( meaning, you buy a bigger number than the one that is installed if you want to richen the mixture at low speed or you drill/file it out) If everything is clean as you say, then the unit needs a bigger low speed jet... The definition of crazy is doing the same thing over and over again and expecting different results.. Check with Trouts, he may have a larger low speed jet number he could trade you off that old carb or off a different unit carb.. Good Luck, Friiy

Good stuff Friiy. 

.....confirmed the dumping of carb spray into the air jet with the spring should produce a decent spray, not drip, into the throat on the same side as the jet.

Spraying in one of the back holes on the maifold side should produce some liquid from the air exit port on the top of the carb.  There are two bosses on the top at right angles to the throat.  One of those should have a hole and possibly a right angle with a piece of short hose on the end.  That's a vent and where the dribble or air should come out when you spray from the back.

On the top of the carb is a screw with a fixed metering hole.  If you spray in there the cleaner should end up in the bowl area.  There are a few places it may come out of depending on the carb. 

One place is at the bottom of the center tube.  On some carbs there is a small hole at the bottom of the inside tube wall.  A second tube is cast into the main tube.  The second tube usually has a small ball pressed into its end.  Above the ball there is usually a small hole.  When you spray from the top fixed metering jet liquid should come out of the second tube hole.   It should spray out and not dribble.  Your carb may not have the hole at the bottom. 

There is another possible route higher but you should can see liquid comming out of the center tube. 

The above possibilities I think are all in the low idle circuit.  In general when you spray into a port cleaner comes out as a spray or dribble either in the throat or bowl area, most often a spray.  Your carb had the thin varnish and the thick goo probably from evaporated oil.  The chances are high the internal passages are still plugged or partly plugged.  That's a good reason to prod well, dip, dump in lots of carb spray and high pressure air.