I was cutting my lawns today and halfway through the mower started running slowly, approx 1/2 throttle. It is a Mountfield Omega 46cm (18") hand propelled with a Briggs & Stratton 3.5 HP engine. At first I thought it was the petrol running out so I looked in the tank and it was nearly empty. I filled it up and it was still the same. I did all the usual things, clean plug, air filter, set plug gap etc with no effect. If I pull the throttle lever it revs OK. I took the starter lid off to look under there and nothing seemed amiss as far as I could see, the fan blades were intact and the flap that is moved by the air from the fan blades moved easily enough.
There is a block made up of lots of layers of thin metal at the front of the engine that I presume is a coil type thing as the HT lead comes out of it. I noticed that this was touching the big wheel in the middle at one side and not at the other. What is the correct positioning for this bit and is it supposed to be magnetic as it isn't?
Any ideas anyone? Any help greatly appreciated. Failing that anybody know of a good lawnmower service man in the Leeds area?
Cheers
John