Briggs and Stratton 286707 uneven running

[shytalk]

I have a Countax ride on Tractor here in England. It is fitted with a Briggs engine reference 286707 which has a gravity fed LMT Walbro Carburettor. The engine starts easily but at normal temperature and maximum revs it runs for about 2 minutes then 'splutters' for a second or two then runs normally again then the cycle is repeated. I have fitted a new spark plug RJ19LM and use new fuel. The air cleaner is good and I have washed and oiled the prefilter as per the instruction book.

Any ideas what might be causing this problem please?
Thanks in advance for any help you can give.

 

[reb]

Sounds to me like it is time to dig into the carburetor. Maybe a sticking or incorrectly adjusted float valve. Might want to check the fuel filter first. Let us know what the problem is when you get it fixed. We might learn something.

 

[bindian]

I don't remember the model numbers. Is this a twin cylinder Briggs? The older twins had a diapharm fuel pump. The diapharm might have a hole in it. I once overhauled my Dad's 18 horse twin Briggs on his Gilson lawn tractor. Sometimes it just ran better with a little choke. If you do rebuild the carb, have it cleaned in an ultrasonic parts cleaner. Also, as I remember, the governor linkages on the twin are complex. Make sure it is working right.
hugs, Brandi

 

[DJ54]

I second a good carb. cleaning. Be sure and remove the discharge nozzle, and check to make sure the cross drilled holes are clean & open. A single wire from a wire brush, or strand of copper wire from a section of automotive 10-12 ga. wire make a good cleaning tool.

 

[3930dave]

A second vote for replacing the fuel filter, if it has one. Take a peak inside the gas tank with a good flashlight, checking for debris in the bottom of the tank, and also water contamination. I've seen lawn equipment that is stored outside have globs of water sloshing around in the bottom of the tank.

As posted, the carb may have to come apart for parts replacement/adjustment. Before doing that, if you haven't already, try dosing at the recommended levels with a good gas treatment/carb cleaner.

Seafoam is commonly available here.... but I'm not sure what is stocked in the UK.

Sea Foam Motor Treatment (Seafoam)

P.S. - I'm meaning add to the fuel tank, and run the engine. Seafoam (or equivalent) can be used other ways, but would likely be the most help added to your gasoline.

Best of luck. Rgds, D.