Have just replaced carb diaphram after mower suddenly stopped working. Cleaned plug - very sooty - cleaned out tank and renewed air filter. Engine starts but revving much too fast. Governer/idler springs appear to be correctly fitted. Help appreciated.

Kim, August 2008

Slightly bend back the idle speed adjusing tang on the throttle plate this will reduce the speed.

pleasant, August 2008

Thanks Phil. Neither spring is twisted and there's very little tension on either. It's a Mountfield with a Classic engine (Model 9D 902 Type 2006) which my Briggs manual says has the idle speed set in the factory and is non-adjustable. When I push the throttle shaft in the opposite direction ( the V shaped piece which attaches to the air vane link, the revs drop - but it doesn't seem adjustable). Any thoughts? I've changed the diaphragm which seemed to go back alright but wonder if that is the problem?

Kim, August 2008

I can guarantee that either the govenor vane is jammed, or one of the springs is twisted/caught up on something. Speed is controlled by the tension on the large spring - there is nothng else connected to the carb throttle plate.

If the plug was sooty, you will also need to replace the carb diaphragm - do this at the same time. Only takes 10 mins.

phil_saunders@bigfoot.com

Phil Saunders, August 2008