My mower has not been run for a while. When I start it and take off the choke and put it at high speed, the engine revs up and down. There appears to be a throttle linkage of some sort that is moving back and forth by itself causing the up and down reving action.
Can somebody advise me on repair?
Thank you
John

Replace the throttle linkage and ajust the idle speed

Are you referring to the governor? Could be missing a spring from the governor, or throttle plate.

Did you drain the old fuel out of the tank? It sounds like you may have some water in your fuel. Be sure to drain the tank AND the fuel bowl (the little metal cup the fuel line goes through before entering the engine). Water in the fuel is usually the culprit when the engine behaves the way it sounds like it is.

turfman, I see you are new here. Please read the rules about giving red marks first before giving them out. Mowerman is one of the best experts we have here. He has helped out more folks here than you can count. He knows his stuff. We all give out expert advise for "FREE". Read his profile and his other 2,074 post here before giving him reddys

Jbs, where are we on this issue?

All of these answers still relate to the carb. If this mower has been sitting it could be a combination of problems. Dirt , water and corrosion in the carb should be cleaned, the float and float level should be checked, all jets should be cleaned and new gaskets should be installed. It also could be air entering through a loose carb or damaged gasket.

I had the same problem and discovered that it was caused by over filling the gas tank, which caused the small sponge in the gas tank cover to be saturated with gas - which prevented air from entering the tank - which caused a vacuum to form in the tank - which prevented gas from entering the carb. To fix, remove the rubber gasket from the inside of the mower’s gas tank cover and take out the small sponge. I’ve been operating without the sponge for a few years now. Of course, there’s still a possibility of a carburetor or governor problem, but removing the sponge is a very simple, first remedy solution.