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.

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.