I experienced a swollen seat in the carb on a B&S Eng, MTD mower. The mower stalled just as it would be running out of fuel but had fuel. I could see the differences in sizes after purchasing a new seat. Plus a small Eng Tech verified this was common with untreated corn fuel.

Initially I thought the seat was too small but a little force seated it where the well gets smaller. You might measure the seated seat with a drill bit and compare it with a new one if you have a small Eng Shop close.

I possibly can spot a carb # if neded.

We own an Ariens snowblower, with a 6 hp Tecumseh engine. It does hunt and stumble a bit, but when loaded and working, it calms down and operates smoothly. The engine starts reliably, on the first pull, with priming. To keep the carb clean, I always and without exception stop the engine by closing the fuel valve, and wait for the engine to stall, having used up all of the fuel in the carburetor. You might try to add some "gum-out" or similar product to the fuel tank, and operate the engine for an hour or so. It is OK to do this once per season, but not a good idea to run carb cleaning agents continually, because the solvent might damage any polymer parts in the fuel system.

The chemical in fuel carb cleaning is a start and good option if gasohol has been used and left in the carb while it is stored out of season. What we need is a good “Old School Glass Fuel Bowl”. LOL! That might show some of the problem of the seat not letting enough fuel into the system. A fuel drain button on the bowl could serve just as well to check for fuel “But, Be Careful On A Hot Engine”. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

The bottom line is history of maintenance and respecting signs of problems and attacking before they catch you at a bad time. Is a filter or fuel screen in the system? Is it possible rust could be developing in the system? Have you ever completely disassembled, inspected and cleaned the carb?

IMO. “hunt and stumble a bit, but when loaded and working, it calms down and operates smoothly.” To me this is a governor vs using power w/o a load. “Fuel Starvation is a lack of fuel due to an adjustment, restrictions, water, Etc”.