Mend > Lawn Mowers

Mend Sears 12hp OHV Craftsman Riding Engine

carburetor adjustments?

I have an older craftsman riding mower with a 12hp ohv tecumseh engine on it. I am having a problem with gas flooding the carburetor when I open the in-line shutoff valve. I have cleaned the carburetor and need to know the basics for adjusting the carburetor in order to eliminate the flooding issues.

Jim Quattlebaum
April 2009

Sears Sears 12hp OHV Garden Tools, Lawn Mowers Craftsman Riding Engine

Jim, this is due to the needle valve sticking open on the float chamber. The float chamber is a round bowl at the lower half of the carburettor, usually held in place with a central bolt. Undo the bolt and the chamber will fall free, exposing the plastic float inside which hinges on a pin. Carefully push this pin out to release the float, and you'll see a small needle that pokes into a brass housing. This is where the fault will be - some dirt is holding the needle valve open causing your flooding, and it needs to be cleaned. Its much easier if you can undo the carb. and work on it on the bench! The only other adjustment is the pilot mixture screw, which should be 1 1/4 turns out from fully in.

John
April 2009