Craftsman 13.5 mower runs very rich part of the time.
I have a relative late model Craftsman rear-engine Briggs 13.5 engine, and have had trouble from the git-go.
The engine starts easily, and "sometimes" runs smoothly. However, about 50% of the time it "sputters", and misses a few licks -- black smoke comes out the muffler, and the thottle with "automatic choke" doesn't seem to change anything but speed. Occasionally, the motor smooths out, though (not rich), whether the blade is engaged or not.
I can't tell any difference from in the choke position or 1/2 throttle, except the engine shanges speed, so I presume
1) the choke is not functioning properly, either "floating" wherever it wants to and
2) the governor apparently works.
It has been back to Sears a couple of times, under warrantee, and the last time was out of warrantee, at a cost of about $300 -- still same problem. HELP!