# Briggs and Stratton 18hp problems



## gsl54 (Apr 29, 2012)

At idle the engine seems to run fine, but when I engage the mower deck it starts to sputter and backfire. Most of the time it eventualy smooths out till I get into thick or tall grass then it starts to backfire. I have not cleaned or rebuilt the carb. I have been told it could be the govenor. It is on a 12 year old AYP/Rally. any suggestions would be appreciated. Thanks Garry


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## jhngardner367 (Apr 5, 2011)

Garry, try checking the fuel system,for plugged filter,etc. If all seems good,check the carb adjustment ,and governor setting.


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## dangeroustoys56 (Jul 26, 2010)

When was the last time it was tuned up? It could be due for a carb cleaning/ rebuild kit as well - the gaskets inside absorb gasoline and eventually break down allowing gas to go places it shouldnt .

I had issues with one of my twin cylenders, it wouldnt run right, no matter how many times i cleaned it - i put a rebuild kit in the carb and the fuel pump - runs whole lots better.


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## gsl54 (Apr 29, 2012)

I replaced te fuel filter, rebuilt the carb still having the same problems.


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## Country Boy (Mar 18, 2010)

First thing I'd do is to perform a leak-down and compression test on both cylinders (I am assuming its a twin). See what that shows. I'd also check to be sure the flywheel key is intact and not partially sheared (affects ignition timing). Could also be a bad ignition coil giving you a weak spark. I doubt the governor would be the issue. If they fail, the unit would start to run excessively fast.


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## gsl54 (Apr 29, 2012)

Thanks Country Boy, I will give that a try.


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