when engine is not under load it surges (decreases rpm then increases rpm back and forth) when I engage the mower deck it isn't as noticeable , I think it's the governor or the carb, How do I adjust it if this is what is causing this? thanks

dan, May 2009

Same problem here. Once upon a time it cleared up by itself, but now it's back. The simple fix for me is to simply run it richer, adjusting the choke until it stops. The other solutions sound expensive and ineffective.

tbr, December 2009

Does the engine run smoother when you pull the choke out?

PJB, July 2009

I've had the same problem for several years. One time, cleaning the carbon deposits from the cylinder head helped the problem...for a few months. The next time I took it to a repair shop, who re-built the carb for $400! It fixed it for a season. The next time I bought a rebuilt carb for $99. This, again, worked for a season. It is starting to do it again this spring :(
It must be something fuel-related, but not sure what. The $99 rebuilt carb almost seems like the easiest "fix"

Jon, June 2009

Hi my father had the same problem, it was a $600 fix the motor is junk, it has a bad top end, when the engine gets too hot it burns out the valve seats, the dealer put some kind of putty to seal it, but it,s doing it again. briggs discountinued this motor and you can't even buy a replacement top end for it, if you have any luck finding parts please let us know this was a $2500 machine

Carl, May 2009

I have the exact same problem. I was told it was a vacuum leak in the carburetor, so I rebuilt it. Now it is still surging. Here is the strange part: When I took the fuel pump apart, there was not the big spring inside,only the ring. The insructions show the spring, so I put it in, but then it wouuld not start and fuel was coming out the bottom of the pump. I took it aprt and took the big spring out and then it started right up. This makes no sense to me?????? I am the original owner and it did not surger before.

Ron, May 2009