Small Engines (Lawn Mowers, etc.): lawn tractor idle problem, craftsman lawn tractor, ohv engine

Question
My craftsman lawn tractor with a Briggs OHV engine will only stay running in full choked throttle, when i back it down to normal running throttle it idles up and down and then shuts off. Any ideas?

Answer
Steve
What you need to do is rebuild the carb as it has problems with junk in the fuel ports
The most important PM that is not likely done by 90 percent of mower owners is to drain the gas at the end of the season. With float type carburetors in particular, the result is a buildup which eventually clogs the very fine passageways in the carburetor. What happens is that the gas in the carburetor bowl gradually evaporates leaving behind the gunk and varnish. New gas then flows in from the fuel tank which then evaporates leaving behind more gunk and varnish, and so on and so on and so on. This eventually, well, gums up the works by interfering with float movement and clogging the precision metering holes. Thus, the need for cleaning. Symptoms include difficulty in starting, flooding, surging, lack of power, difficulty in restarting when hot, etc.