Mountfield Lawn Mowers

[douggym]

Help!!! My mower is sick. I have recently cleaned the air filter and changed the oil in my Mountfield 14" Rotary Lawn Mower and it is now very sluggish. It has a full petrol tank and starts up ok after priming but after a few seconds of running well the engine slows right down and is running at justabove stall speed. It cuts grass ( not well) but as soon as it is put under any strain it stalls. If I tilt the machine back slightly the engine picks up but then slows down again. Could there be a fuel blockage or is it something more serious? If it is a blockage, how can I clear it?.

[Thunderbird+]

A fuel blockage was my first thoughts, as I read down through your post, possibly sediment in the tank or carberator / float bowl. Otfen fine dust particles can find their way in these places, check these places, clean and flush it through if nescessry.
It could also be a case of a slight adjustment of the air screw. But if in doubt contact a good mower shop and get it checked out by a qualified mechanic. Good Luck.