QuestionEngine started fine, ran well, but at end of mowing job, engine would not cut back to idle. All linkages seemed OK, governor spring OK also. Nothing sticky. Stopped engine by disconnecting plug. On several restarts, engine went to high speed, no throttle control at all. Was concerned about runaway, so always disconnected plug promptly. Tried adjusting low and high speed jets, had no effect. Did not examine throttle plate. Choke plate operating normally.
I'd bet this isn't a common problem. Is there an easy way to test the governor by moving the arm manually? As I say the spring seems fine. Could there be a huge air leak somewhere? Never seen anything like this before!
Please advise on where to begin. I do not have the engine here now but would like to begin diagnosis as soon as I return to my camp.
Thanks very much for help!
Frank
AnswerThere's quite a number of things it could be. A bad head gasket, an air leak in the manifold or carburetor, fuel restriction in the carburetor, a stuck throttle, a stuck governor and probably a few more. With the engine running you should be able to manually move the throttle and see if the governor responds.
I'd probably start with the carburetor since the mixture screws don't change the engine speed.
