The Kohler Magnum-12HP on My Woods Mower Runs Well for Awhile Then Stalls Out

Contaminants

• The Kohler12HP Magnum has a fuel system that contains fuel lines and filters. If any of these are obstructed by debris or sediment, fuel delivery will also be obstructed. Prevent this by ensuring that the fuel tank is closed when the mower is not operating, and that only the vent is open during operation. Regularly check and replace the fuel filter as needed.

Fuel Pump

• The Magnum’s fuel pump pushes fuel into the carburetor through another fuel line so that the carburetor can mix the fuel with air. A faulty fuel pump may push fuel intermittently or not at all, causing a start with a stall-out. Fuel pumps can fail if the fuel pump lever breaks or the diaphragm cracks or leaks. If this happens, you cannot replace the individual pieces. Rather, you must replace the entire fuel pump assembly.

Choke

• The choke system gives you the option to add extra fuel into the carburetor for a richer mixture. Normally the choke is operated by a throttle so that you can open and close it. If the throttle fails to close the choke, too much fuel will enter the carburetor and flood it. Check the choke lever to see if it’s opening or closing when the throttle is actuated. Also check the throttle controls themselves.

Vent

• The fuel tank on the Kohler 12HP Magnum has a vent on top of the cap. This vent allows for good air flow into the tank as fuel is pushed through the fuel line and into the fuel pump. If this vent is compromised, there may not be sufficient pressure to keep the fuel flowing, especially if the tank is partially full. Check to see if the vent is fully open and free of debris.