My riding mower runs too fast and the throttle won't slow it down, why is this happening?
I cannot control the idle speed of my Wheelhorse lawn tractor. The throttle cable is intact and the idle arm, etc. moves the way it should. Adjusting the air, fuel, and idle screws works for a short time but then the engine starts racing again.
The engine is a Kohler, Magnum 16, 16HP, model# M16S, spec.# 711523, serial# 1801506744
Is it a carburator problem..?? Any info would be appreciated.
Fuel level in the carburetor bowl could be a little high. Excess fuel is then "spilling " or being drawn into the bowl. Usually a small spec of dirt is preventing the feed valve from closing OR the float has lost some of its buoyancy . A dirt issue is usually accompanied by fuel leaking and flooding the carburetor when the engine is off. Loss of buoyancy of the float may not cause flooding when the engine is off. But vibration of a running engine combined with the loss of buoyancy prevents the feed valve fro fully seating.
Another cause is a dirty air filter, this acts as a choke and causes the engine to pull a higher vacuum which in turn pulls in more fuel from the spray bar.
Engines also have a speed control linkage. This is a paddle or blade attached to throttle linkage. The cooling air from the blower on the engine works against this paddle to operate the throttle and regulate speed. If debrie has built up behind the paddle then it won't work properly to control speed of the engine
