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

I have been working to get an leaf loader ready for fall clean up. The 11hp briggs and stratton engine starts briefly when choked and then dies. Gas runs out and drips below. It runs all of 3 seconds before it dies. I've tried starting it without the choke but no luck there. When I bought it a week ago the previous owner started it on the first pull. It has a good spark, fresh gas, a clean air filter. With the spark plug pulled I can see the spark. I've tried starting it at half throttle, full throttle and low throttle. No difference there. I took the bowl off the carburetor and cleaned out the crud that was in there. Do I need to take the carb off and completely clean it? What setting should the throttle be at for start up? Any suggestions? the motor is a Briggs Industrial Plus model 256422 type 1015 -E1

Is fuel comming up the main nozzel in the carb behind the choke butterfly when it floods? If so the needle/seat/float is causing the problem...

or...
The fuel pump may be leaking internally to the "vacuum side of the Diaphram", meaning that the fuel is making it to the carb also through the vacuum port on the intake manifold..(I think that is where the pump hooks up on this motor, correct me if I am wrong...)

Try starting the motor with a pair of vice grips on the Vacuum line from the pump after the bowl is already filled with gas. If it still leaks this will rule out pump vaccum side failure...

Try taking the pump completely out of the loop, hook up a fuel tank and gravity fill the bowl of the carb with it... If you have a float/ needle/seat problem, the carb will leak by gravity feed also..


Good luck,

Friiy


Ps.... How did the tiller work this spring?

<BR> friiy wrote: <BR>With the air filter off, I do see fuel in the carb behind the choke butterfly. But I cannot confirm that the fuel is getting there through the nozzle as you suggest. I went ahead and replaced the fuel pump yesterday with a new one and it no longer drips. Without the fuel pump the carb does not get gas (the tank is slower than the carb). When you pull the starter and let the bowl drop down the fuel flows right through (I catch it with a cup). If you raise the bowl up with your finger, the fuel flow stops (even if you continue to pull the starter cord). I spent the day yesterday cleaning things I got the main nozzle out (carefully) and cleaned it really well. I installed a new fuel line, the new fuel pump, a new fuel filter and flushed the gas line. I slid small wires through the little holes and used a can of carb cleaner with a straw tube to blast the cleaner through all the holes that I could see. The I ran my compressor up to 100 psi and blew everything out. I also put in a new spark plug and changed the oil. <BR>I pulled the starter cord (choked on) and the engine fired right up and the died quickly. If I let it sit for 20 minutes and leave the choke off, it will fire right up again and then die. I'm baffled. I'm stumped. <BR>It really was running fine when the previous owner started it just over a week ago. That's why I purchased it. It ran so smooth. <BR>There is a small white wire dangling unconnected below the carb. Maybe something came disconnected. <BR> I thing I'm missing something really basic. Something foolish. The leaking fuel pump was just a distraction. <BR>Is there a factory setting for the idle mixture screw. I got that off by removing the safety shroud around the muffler but I'm not 100% sure I got it back where it was set before. <BR><BR><BR>The tiller is fantastic. I had used a front tine Merry tiller before but there's no comparison. My neighbors have all borrowed it as well. I'd like to add a sickle bar to the BCS someday. <BR><BR><BR>

Sounds like you still have something in the fuel system plugging the high speed circut... Does the carb tower (post that runs through the float that the bolt screws the bowl on) have a jet on it, or is the jet drilled into the bowl bolt? Check these for grit that may have settled there.. Post pictures of the carb with the bowl off, if you would.

Don't worry about the idle mixture screw at this time, set it at about 1 and 1/4 out from soft stop.. That low speed circut is not running unless the throttle shat is almost fully closed. Adjust that after the unit is running, warmed up and at idle.

So, is the carb not leaking any more? Are you sure the bowl is full of gas?

Post some pictures of the carb with the bowl off if you can..

Good luck,

Friiy

I'll work on getting some pictures of the carb. I know that there are some hole that I could not reach without removing the float (I did not remove the float because I did not remove the carburetor from the engine, I've never taken one off a Briggs and I was worried I'd ruin something. On the outside (air intake side) of the choke plate I found some small hole to clean. But I have a feeling that there may be more of these holes further in near the other (throttle?) plate. I could not reach those. This afternoon I pulled it and it ran (rough) for almost 10 seconds. &
Question: When I slide a small metal wire down the hole on the left side of the carb it goes all the way in. When I try to do the same on the hole on the other side it only will go in 2 inches. (Cycled in green) I'm not sure if this is normal. <BR><BR><BR>&gt;<BR><BR>This is the location (yellow square) that I could not reach without removing the float. &lt;BR&gt;&lt;BR&gt;&lt;BR&gt;&gt;&lt;&lt;

The holes on the carb are the emulisfier vent and the carb bowl vent.. I could not tell you which is which unless I had more pictures. The holes go in so far and then are drilled 90 degrees through the access behind the welch plugs (silver discs pressed into carb body).

The carb bowl vent keeps the carb bowl and fuel at static pressure (outside air pressure)the low pressure of the air in the venturi draws fuel through the main and low speed jets...

The emulsifier jet is a port that injects air into the main jet fuel stream (through all the little holes in the nozzel) so the fuel "sprays" instead of bubbling up and pooling in the bottom of the venturi..

Don't worry about the wire not going through. Just spray in the hole and make sure it comes out the vent above the float and the emulsifier jet comes out where the nozzel screws in...


Good Luck,

Friiy

friiy wrote:

When I look into the carb while pulling the starter I don't see gas being sprayed.  Instead I see it bubbling up and pooling around the top of the brass nozzle. Right behind the choke butterfly  where the brass nozzle pokes up and enters the carb.  Where is the venturi?

  

The spray shouldn't happen till the engine is running. On Choke-starting with a pullstart, a large vacuum is created to draw "rich amounts" of fuel into the venturi..

The venturi is the narrowing throat of the carb in the middle...(as air velocity increases at the venturi, pressure decreases, thus drawing fuel through the jets to the low pressure area)

I don't understand, is the carb still flooding when it starts to run, or is it acting like it is running out of fuel? Was fuel bubbleing out of the carb as it stopped?


Friiy

friiy wrote:
I oppologize for my poor description. I'm starting to understand how a carburetor works (thank you). With the choke I can see a small wet area forming in the "ventury" area where the brass nozzle sticks up. Then engine starts and then stalls. Previously, when the bad fuel pump was dripping gas down the side of the engine I thought the gas was coming from the throat of the carb (flooded) but the plug was always dry. I ran some more carb cleaner through the little holes and then blew them all out again with the compressor. The engine roared to life and did not die. It ran and ran and ran until I tried to bring the engine back down to an idle. Then it cut out. I'm going to look for the factory settings for the idle screw. PROGRESS!

Well, back to square one. When choked the engine springs to life and as you open the choke it rev faster and faster until it dies about 5-6 seconds later. Pulling the choke back closed again does not keep it running. Nor does changing the throttle. I'm back to the drawing board. I am learning though.

I you can start the engine and only run it on choke, and the carb is still full of fuel when you take the bowl off (provided you have not pumped more into from try to pull start it again). Then the problem is mostly still in you high speed circut. I think you should check the nozzel again, after you clean the nozzle, clean the little hole that goes into the carb tower that allows fuel to enter the nozzle, this little hole(main jet) should intersect with the smooth area of the nozzle...

The hole you need to clean is just above the yellow box on the cutaway carb photo just below the float(aug 30, post picture).. this would be the "main jet" that all fuel travels in the carb..( this jet may be a press in, unremovable or screw-in)

http://outdoorpowerinfo.com/repairs/images/kohler_walbro_lmk/_main_jet.JPG


This photo shows the "main-jet"


Friiy