# B & S Engine Fires but won't stay running



## spelunk73 (Sep 16, 2013)

I have a small Briggs and Stratton powered push mower that is giving me fits. I usually have no problem repairing small engines but this one has me puzzled. It will start when primed with the primer bulb, but it will not continue to run. I have removed the carb and cleaned thoroughly, making sure all the orifices are clear of debris. This carb does not have any adjustment screws. Also, the O-ring for the intake tube is fine and the intake tube gasket it in good shape. Occasionally it will start and run for a minute or two and then die again. But for the most part, it will only start when primed and then die as the primed fuel is used up. The needle and seat are in good shape. The carb bowl fills with fuel as it should. The float is working. Everything that I know to check seems to be in good working order. ANY IDEAS??????


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## OptsyEagle (Jul 17, 2007)

You could try it with the fuel cap off to rule out a gas tank ventilation problem.


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## 30yearTech (Sep 14, 2006)

Sounds like the float bowl may not be filling up with enough fuel. Did you replace the float needle seat? Sometimes they swell up enough to restrict fuel flow into the carburetor.


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## spelunk73 (Sep 16, 2013)

I did not replace the needle seat but I have plenty of fuel flowing into the float bowl. And yes I did try without the fuel cap on. It will start after priming the engine but dies within 2 or 3 seconds. Only a couple of times did it actually stay running for about a minute. May 2 out of 60 starts. It started back to back then continued to do as it did before. Prime - start - die. I am so confused lol


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## geogrubb (Jul 28, 2006)

Since you didn't post the engine numbers but mentioned it had a bowl I will guess that the problem is the bowl nut which is the main jet is clogged, refer to the pic below, clean all the holes, one through the center and one across the bottom. Have a good one. Geo


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## spelunk73 (Sep 16, 2013)

Already cleaned but to be safe I disassembled the carb again and cleaned thoroughly again. Still same result. Prime - start - die - repeat

Here are the engine codes Model Type Code
12F702 0606-1 94082656


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## Rentahusband (Aug 25, 2008)

I have a micro size drill bit set to clean the holes in the bowl nuts. Wondering if you used something similar to clean the holes in the bowl nut? Sometimes carb cleaner is not enough to clean these holes. Sure sounds like it is still a fuel delivery issue.


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## geogrubb (Jul 28, 2006)

I had one that drove me crazy, it had a tiny piece of grass or something that worked like a flap, when I sprayed cleaner through the bottom holes it moved to the center hole, when I sprayed through the center hole it moved to the bottom hole, after the second try and no luck I ran a wire through the holes and out came the piece of grass. Have a good one. Geo


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## rtgirard (Jun 7, 2012)

For the really tiny holes, I usually steal the twist wrap off of a loaf of bread (when my wife isn't looking). Just strip off the sheath and the exposed wire is usually small enough to clean out any tiny holes in a bowl nut.


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## spelunk73 (Sep 16, 2013)

Not sure what I did but it seems to be running fine now. Must have still had something blocking the fuel in the carb. Not sure, but it appears to be working fine. Thanks for all the help. Sure would have liked to have found the problem so as to maybe help someone else in the future.


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## 30yearTech (Sep 14, 2006)

Probably something like what plagued geo, it doesn't take much to restrict fuel flow through the jet or nozzle and you could have removed it without even noticing.

It's great that it's working good now... :thumbsup:


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## spelunk73 (Sep 16, 2013)

It was running GREAT until I hit a rock and bent the shaft on the motor. I guess this mower was doomed for the scrap yard one way or the other. I am going to try to heat the shaft and straighten to get some of the wobble out but usually don't have much luck with that. Oh well. Thanks for all the help


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## usmcgrunt (Sep 16, 2007)

I would caution you to not try and straighten the crank shaft.Once heated,the tempering of the steel will be made softer and the chance of shearing off and being launched will increase dramatically.Heating the shaft will also ruin the rubber oil seal.If the mower is in good condition,replace the crank shaft or switch out the motor."IF" your lucky,the crank will be OK and only the blade is bent.


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## Don L (Jul 14, 2012)

When I was about ten years old I saw the end of a lawn mower blade go through the rear quarter panel of '58 Chevy.These cars were made out of real steel,just imagine what it would do to your leg.


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