I have a Sears lawn mower with a Briggs and Stratton 6.5 HP engine. The mower is about 6 years old.

The engine starts well, but after a minute or two, it begins to enter an oscillation cycle-- the engine starts to lose revs, then it picks up again. This process continues, each time the engine getting lower in revs, until it finaly cuts out.

I've been told that the float in the carburettor may be sticky, and I've added some carb cleaner to my fuel, but the cutting out continues. Does anyone recognize this problem and can anyone recommend a solution? Do I need to replace the carb, and if so, how do I get a new one?

Simon, September 2004

Your problem is fuel related by the sounds of it. Remove the carb and flush the fuel tank. These carbs are very easy to clean. Make note where the springs go when you take it off. Remove the carb bowl and clean. Using a can of carb cleaner spray all small holes in the carb checking for any clogged ones. They can be cleaned out with a small wire.To check your float for leaks hold it up to your ear and shake it, if you hear anything in it replace it. There is a small hole in the front of the carb, make sure it is clear. Reinstall. I recommend new fuel and use fuel stabilizer in it. It cleans your carb and keeps your fuel fresh for up to 2 years. It can be purchased at most stores that sell lawnmowers. Good Luck

JOHN at Rona, September 2004

Have you checked the engine over-rev regulator ? a lot of engines have an aluminium flap close to the flywheel .. as the engine gains speed this flap will cause the throttle to close ...... it might need oiling , and/ or the the connection to the throttle checked .
jets blocked ?
Al

AL, September 2004