I was by my brother-in-law’s house today and he asked me to look at his strangely acting lawn mower. I didn’t know how to approach fixing it, so I’m hoping someone here has an idea.
It’s a Murray lawn mower with a 2 hp Briggs and Stratton engine. It has an automatic throttle, so there’s no adjusting engine speed.
The problem is that it revs fast slow fast slow alternating speeds about once per second. The linkage moves by itself. I have a feeling there’s a simple fix, but I couldn’t figure it out. Anyone?
Not sure how old it is but it might have a vane air throttle control. The engine would have vanes in the top spinner that acted against a vane that was connected to the carb throttle. Either the vane could be jammed by yard debris or the spring broke connecting it.
Yes, there is a connection that seems to be controlled by the spinner. It’s not clogged anywhere. I’ll check if there seems to be a connection for a spring. Thanks.
Is the oil level OK, and not too old? Briggs & Stratton engines use an air vane governor, but Tecumseh engines use some sort of oil activated mechanism…never had one apart, but the governor arm comes out of the crankcase. Old oil, or low level will mess up the speed control.