I've got a throw away MTD mower with a 16.5 hp Briggs I/C engine that has a surging problem that I can't figure out.
It acts like there's something goofy with the governor but I'm not sure if it's internal or what. With the throttle wide open it revs between full throttle and about half throttle and I can watch the governor arm move back and forth opening and closing the throttle. Below about half throttle it just dies. If I engage the deck it smooths out and runs better. Pulling the choke cable out a little helps smooth it out too but it has no power with the choke on.
Before I tear into it, I'd like to know if it's something I can fix without opening up the engine to look at the governor.
I've already looked at the carb but it's a fixed jet with no adjustment. I also checked for vacuum leaks between the carb and engine.
The only reason I want to fix it is so I can sell it this spring. It's getting replaced by a Cub.:biggrin2.gif: