My Craftsman Lawn Mower Doesn't Run With the Choke off

Gasoline Quality

• Stale gasoline can lack volatility but may still fire an engine with the choke closed. Drain out any fuel that has been stored for a month or longer, and add fresh gasoline to the tank. Fuel gumming and light varnishing may be dissolved by the fresh fuel after soaking in for an hour or so. The fuel tank filler cap must vent properly. Clogged vents can create a vacuum in the tank, ceasing fuel flow. Clean the cap surfaces and vents.

Fuel Hoses

• A rubber fuel hose can rot internally with no outward sign of any deterioration. Remove the hose from the engine while the tank is empty or the fuel valve is closed. Ensure the hose is empty and away from your face, and look through it. Check for collapsed material inside the hose, and replace any fuel hose with soft spots or cracks. Inspect the fuel filter element if visible through clear plastic housing. Replace the filter if no inspection is possible.

Fuel Cleaner

• Minuscule passages in the carburetor direct air and fuel flow for differing engine conditions. This precise plumbing can become clogged with deposits or varnish from stale gas. Add bottled carburetor cleaner to the fuel tank in the dosage recommended by the product manufacturer. Allow an hour or longer for the cleaner to permeate the fuel system. You can drain the standing fuel from the carburetor to speed the process if the carburetor float bowl is equipped with a drain plug.

Ready, Steady, Go

• Start the mower and monitor engine performance at various throttle settings to check for improved performance. Shut the mower off if problems persist after 5 to 10 minutes at full throttle. Let the mower sit overnight to allow more time for the carburetor cleaner to work its magic. A carburetor overhaul is indicated if no improvement is realized the next day. Carburetor overhaul procedures vary for different makes and models of Craftsman lawn mowers.