Hi, its a quick fix. Just check the springs at the front that go to the carb. What I did was remove the smaller spring just leaving the throttle return spring in place. It throttles up high and wil then settle when you start and should then be okay.
It may be that the front bracket the springs attach too have been bent when mowing near a tree or something.
john
September 2008
This could be a symptom of the throttle govenor bracket at the front of the engine becoming bent back whilst using to mow under bushes or trees. Will need adjusting forward to increase engine speed. Black smoke and lumpy running is a symptom of a worn diaphragm.
pleasant
August 2008
just done mine same problem ..new diaphragm runs better than new £1.90 plus vat an its a good un ..
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix lawn mowers.