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stuck on a simple B & S quantum engine

1587 Views 13 Replies 5 Participants Last post by  themidniteryder
I picked up a wheeled string trimmer for $20.00 that had been sitting for a few years. The carb was full of varnish but I cleaned it all out and verified the passages were clean. The fuel bowl nut has the gasket and all 3 holes are open and clean on it. The seat had mushroomed out, so I pulled it and replaced it and the float bowl vents out to the atmosphere. I put a new gasket between the air cleaner assy and carb as well.

The problem I'm having is that it will start and run for 1-2 seconds max and then die. Wait 5 seconds, try it again, and same response. The governor linkage appears fine as does the throttle linkage and its all assembled in the correct way. Loosening the fuel bowl nut causes gas to come out at a good stream so fuel is making its way to the bowl. The gas tank was empty when I refilled it so its not an old gas issue.

I'm stumped. This carb is clean enough to eat out of now and its all put together correctly. Next up.. muffler?
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How did you clean it out and verify passages were clean? I would pull it back apart, soak it in carb cleaner for at least 24 hours then blow it out with high pressure air. Don't forget about any tiny bleed passages inside by the throttle plate. Sounds like a restricted passage. Is it a Briggs or Tecumseh, and what model/type/code numbers?
Most defiantly sounds like a carb issue. I would go through it again, it could be a small piece of debris broke loose and is clogging things up again. Like most things of this nature its going to be something simple and stupid. I know, been there and done that. Spent 4 hours last week on a B&S carb issue, engine would run about 15 minutes and die, like it ran outta gas. But it would start right back up. Turns out it was a bad gas cap not letting the tank vent and the suction was stopping the flow of gas just enough.... If all else fails, pick up a cheapie off of fleabay.
The rubber seat, did you get it in upside down by chance?
Carb kit did the trick. Put a new seat in, new needle, new O ring on the float bowl and new O ring where the carb meets the block. She runs great now!
:thThumbsU good job
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