Motor surges

[David K Krohn]

My Model 10A902 is an 8 year old lawn mower. It surges and eats a lot of gas, which it just started doing. I've taken the carburetor off and tried to blow out any foreign particles. Sometimes it helps (temporarily), and sometimes it makes it worse. Is the carburetor the problem? Is it easier to just buy a new carburetor? Thanks!

[Mark]

Hi David,

It sounds like the engine is running rich. You may be able to solve the problem by adjusting the carb. Most likely it will need to be rebuilt or replaced. It looks like the carb for this engine is pretty reasonable priced. I think I would replace it. There are two different carburetors used depending on your engines serial number. The carb is item #90 on the parts breakdown.

I hope this helps with your repair!

-Mark

[Rick Rogers]

I have this exact same problem on the same engine on a 5 year old Yard Machine push mower. The motor surges but won't maintain top end speed. I took the old carb completely apart (not much to it, really) and rinsed it all out w/ carb cleaner. I put it back together and it worked for one weekend. Then I just tried it again today and it's back to its old habits. Once again, I cleaned the carb w/ carb cleaner and it seemed to work for about 10 minutes, then started surging again. I'm not sure if it's just the carb or the governor. The butterfly and governor lever keep going back and forth, like it can't find the sweetspot. Any ideas?

Like Mark posted above, the carb is a reasonably priced item, so it wouldn't hurt to just try replacing it, I guess. But I hope the governor isn't the problem. I'm not even sure how that part works.

RIck

[Dave]

Hi David,

Have you tried replacing the cylinder head gasket? If that's leaking then your cylinder would suck in extra air and would cause your carburetor to fluctuate and the motor to surge or run-rich.

Just a thought.

[Mark]

Hi Dave,

Good insight. A damaged cylinder head gasket could cause the engine to run poorly. It can also lead to dirt ingestion damage as the air going by bad gasket is not filtered. One correction, a bad gasket would actually cause the engine to run lean as more air would be added to the carburetor metered, air / fuel mixture.

Thanks!

-Mark