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fuel problem

Posted by pop890 Texas (My Page) on
Wed, Jul 14, 10 at 12:32

I have a Craftsman 42" mower Model no.917.270812 with a 19.5 hp Briggs & Stratton engine-model no. 42E707,type no.2631-E1.

I'm having a fuel problem. I give the mower a good work out cutting high grass for about two hours. It ran fine. Tried to use it the next day & I had this fuel problem. It will start with the chock out as soon as I push the chock in it dies. Tried to run with the chock out, it will run for a few seconds then starve down for gas.

I have changed the fuel filter & cleaned the air filter & made sure the fuel line from the filter to the carburetor was open. I thought it may be the float but not sure how to get to it. I pulled the metal plate with the rubber bladder off thinking I could get to the float from there. The next part behind the plate is the part that the fuel line hooks to. it did not act like it wanted to come off. So I thought I check with you guys before I messed something up.

I would like to know two things how to get to the float & what else could be keeping it from getting fuel.

Thanks for any help you can give me.

Follow-Up Postings:

RE: fuel problem

Don't concentrate on the float right now, it is not the most probable suspect.
Instead, click the link below and study a similar problem in a different thread.
You have been meddling with the integral fuel pump. Follow my suggestions to clean out the main jet before you go any deeper into the unknown. :^)

Here is a link that might be useful: 'nother 42E707

RE: fuel problem

mownie thanks for helping me on this. When I pulled the plug gas ran out. I removed the jet cleaned it & sprayed back through the jet hole,when I did this the spray came out the top of the carburetor.When I'm cranking the motor spray is coming out the top of my carburetor. Still will not run.


RE: fuel problem

more information. After posting my last message. I was able to start the mower with the choke pulled out all the way. I can keep it running by leaving the choke at least half way out. It is not a real smooth run,but I do think what we did helped some. Should I try running a cleaner through my carburetor or some kind of additive in my gas?

Thanks for your help

RE: fuel problem

Check the condition of the vacuum line running from the bottom of the carb/fuel pump to the engine block, must not leak.

Rig a temp gravity feed tank, hold it above the engine and see if engine runs. IF it does, suspect the fuel pump or tank/gasline restriction.

Sometimes I wipe off the gas tank filler, pace my lips on it and blow to see if this causes the engine to pick up.

WARNING: Let pressure on tank down slowly otherwise gas may blow back into your face, do not inhale fumes.

Walt Conner

RE: fuel problem

Think back and try to guess about how much fuel ran out when you opened the plug on the side of the carb......or, get a container and hold it under the carb to catch the contents of the carb and remove the plug from the carb again.
If you drain maybe 8-10 tablespoons of gas from the carb now (now meaning "since you have been running the engine again after the first drain"), the fuel pump is working.
The carb may very well have a piece of trash lodged in the passage beyond the main jet that is still obstructing fuel flow.
If the engine will idle OK, let it idle for a minute or 2 and then try to open the throttle up all the way.
If the main jet passage still has an obstruction. The engine will refuse to run at wide open throttle from the moment the throttle is opened.
But.............if the engine throttles up to governed RPM for a few seconds (maybe for as long as 30 seconds) and then begins to die, stutter, or lose most of its RPM, you can suspect that the fuel pump is barely operating.

The engine does not instantaneously consume the fuel the exact moment it is delivered to the carb from the fuel pump.
The fuel pump fills the bowl to the level set by the float.
Then, the fuel is sucked into the intake by venturi vacuum when the throttle is opened.
So, when the engine is at idle, very little fuel is being consumed from the bowl and even a weak fuel pump can fill the bowl full.
Cracking open the throttle will permit the engine to draw the maximum volume of fuel flow from the bowl (which is really just a temporary reservoir).
If the fuel pump is weak, it will not be able to keep the bowl full when the engine is drawing the maximum volume of fuel under wide open throttle.
The result is, the fuel level drops and the engine starves for fuel.
If the main jet still has an obstruction, you will not have a few seconds of good running after some idling, instead, the engine will not speed up to governed RPM at all when the throttle is opened wide.

RE: fuel problem

Dude : Keep it Simple , run some carb cleaner (concentrated) through. If this does not solve the problem you may have to remove the jets and spray cleaner within them. I think since it beginning to clear up a good dose of concentrate will remove any residual varnish or gumming issues. If you identify any further flooding issues the needle valve above the float may require cleaning . I would 1st gently tap on the bottom of the float bowl with the handle of a large screwdriver to release the needle prior to bowl removal , with the cleaner additive the tapping may dislodge anything . Always use some form of gas treatment during storage Stabil etc. I always treat my gas during annual start up just for precautionary reasons . I like Lucas Top End Lube / Cleaner myself. Good Luck let us know how you make out .

RE: fuel problem troubleshooting

If the keep it simple technique fails after approx 30 minute duration . Follow Mownies and Watts advice , since Diaphragm or auxiliary fuel pump or vacuum lines may be the contributing cause of the fuel starvation issues . Review carefully Mownies concise Illustrations on the Fuel Circuits on attached previous Thread .

RE: fuel problem

I think we got her fixed. I run some carb cleaner through it. I let it run for about 30 minutes at about one forth speed,then put it up for the night. Started it up this am no problem to speak of give it a good work out for about two hours. Seems to be running good.

Just want to say thanks to all you guys for the information you give,keep me from going off in the wrong direction & making a mess out of something.

Thanks to all. pop890

RE: fuel problem

Great News Pop . I always like to use the KISS Process when ever possible , but advice given by Walt and Mownie was sound had the fuel Cleaner Route not Helped . You are correct the Advice & Illustrations that these Guys Provide is Excellent !

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