The Engine of My John Deere Garden Tractor Will Turn Over But Not Start

Initial Checks

• You must be seated on your garden tractor for it to start. A safety switch built into the seat design interrupts the ignition system function when the seat is unoccupied. This feature is sometimes called a dead-man switch, and is meant to stop the tractor if the operator falls off. Push the brake down completely when attempting to start the engine, or another safety switch prevents ignition function. Ensure the Power Take Off switch is in the "off" position.

Electrical System

• Check the fuses on your tractor in one of two ways. Pull each fuse out to inspect it for any signs of being blown, with the power turned off. Turn the power on to check the fuses with a test light. The test light should illuminate when the probe contacts either side of each fuse. Check the tractor battery for proper voltage and power. A weak battery can reduce cranking speed, and prevent the engine from starting.

Fuel

• Fuel stored for a month or longer may be stale and lack the octane, or volatility to ignite. Replace stale fuel with fresh and allow time for the newer fuel to travel through the system. Inspect the fuel filter for gumming or clogging. Restricted fuel flow can forestall delivery and may contribute to vapor-lock. Vapor-lock occurs when fumes occupy the space where fuel should flow. The fuel vapor heats and expands, blocking fuel flow.

Ignition and Compression

• Check the engine oil level and adjust, if needed. Low oil levels may trigger an engine protection device that prevents running an oil-starved motor. Oil levels that are too high may flood the combustion chamber and foul the spark plug. Inspect the spark plug(s) for fouling, and ensure the plug gap is correct. Use an ignition spark tester to confirm good ignition system function. Use a compression gauge to check for proper internal engine operation.