I am no expert but what I do is to look in the carb.In my mowers there is a kind of well underneath that is held on with a screw.Inside there is a float that swings on a pin and as the fuel enters from the tank the float rises and forces a small bolt up a narrow round chamber-about half an inch long.It has to fall as the level drops though and if there is a sticky gungy deposit-from the petrol- I think it will stick and not move freely.So I clean the little bolt (ideally the whole carb but I don't) and that has solved the problem for me.
gary davies, October 2006
