Riding Mowers & Tractors: Why won't my riding mower move?

If your riding lawn mower won't drive forward or slows down when you go uphill, check the drive belt. Reinstall the lawn tractor or riding mower drive belt if it's slipped out of place. Replace it if it's damaged or broken.

The carburetor mixes gas with air before the fuel goes into the cylinder. If the gas/air mix isn't balanced, the engine won't start or the engine will run rough and stall when you try to drive the riding mower. A damaged carburetor may also leak gas. Replace the carburetor if it causes any of these symptoms.

The carburetor mixes fuel with air to create a combustible mixture that enters the engine cylinder and ignites to drive the piston. Impurities in gasoline can clog the carburetor, preventing the engine from starting. Carburetor clogs can also cause the engine to run rough and the engine may stall when you try to drive the riding mower. Seals and gaskets in the carburetor eventually wear out and can leak gas. Use a carburetor rebuild kit to refurbish a clogged or leaking carburetor.

The engine tune-up includes routine maintenance for a riding lawn mower or tractor. Engine performance suffers if you don't regularly tune up the engine. A poor-running engine may stall when you try to drive the mower. You may notice uneven cuts if the engine doesn't run smoothly when you're mowing grass. Routinely tune up the engine by replacing the engine oil, oil filter, air filter, fuel filter and spark plug. The tune-up also includes checking the ignition, carburetor, battery, throttle and choke controls, as well as cleaning the engine cooling fins.

The seat keeps your body stable as you drive the riding mower and engages the seat switch to keep the engine running while you're sitting on the seat. A worn or broken seat may not engage the seat switch, causing the engine to shut off when you release the brake. Replace the seat if it's damaged or worn.

The seat switch kills the engine if the switch doesn't detect you in the seat when you release the brake. To prevent tampering, the seat switch also stops the engine if you unplug its wire harness. When the engine dies as you release the brake pedal, check the seat switch wire harness to make sure it's plugged in. Replace the seat switch if you find it plugged in but not recognizing your presence on the seat.