My lawn mower started idling up and down a couple of days ago. The up and down idling is constant. Idles up for about 1-2 seconds, and then back down for 1-2 seconds, then back up, etc. Can anyone tell me what the problem might be? It it makes any difference, it's a Briggs and Stratton.

Thanks

 

It Sounds to me like the motor is having a fuel problem I think it is called hunting, anyway, if your b/s has the carb set on top of the gas tank you most likely have a bad diaphgram. Drop the gas tank down, one screw on each side of the carb, with the tank removed remove the old diaphgam and gaskets from the bottom of the carb, observe the small spring under the diaphgram and its position for reassembly. While you have it open it is a good time to wash off the exposed carb innerds with carb cleaner and dump whatever junk might be in the tank and rinse it out. Do not mess with any springs or linkage at this point. Have a nice day. Geo

 

Sounds like classic 'water in the float bowl syndrome'.

Try dropping the bowl, carefully, and look in it. If you see what looks like a bubble in the bottom of the fuel, that's water.

If you don't want to drop the bowl, some have a drain bolt/screw, but keep in mind this may not completely drain the bowl, depending on the design of the bowl itself.

Also this might fix it for a short while and it start again, and it will do this until all the water in the tank/lines has been removed.

Best way to avoid water in the gas is to keep the engine covered if it's left outside, and to keep the tank full. A full tank cannot develop condensate on the inside.

 

I'll give it a try tonight. I appreciate the suggestions.

William

 

WmHeffernan,

I'm not sure what engine you have but if you can supply the engine numbers we will be able to help you better. If your engine has a bowel at the bottom of the carb with a bolt holding it on then remove this bolt which is the main jet. Clean all the tiny holes in this bolt. Some of these holes will be at the base of the nut and may be hard to see. Clean these holes with carb cleaner and fishing line.

God Bless,
dave237