How to Troubleshoot a 455 John Deere Tractor That Won't Start

Check the fuel level in your John Deere 455 tractor and ensure the tank has enough gas in it. Add more gas if necessary. If there is old gas in the tank from last season, add some fresh gas to the tank and crank the engine, allowing the mower to run until all of the gas in the tank has burnt off. Then fill the tank up with new gas before attempting to cut the lawn.

Open the front hood of the tractor's engine and replace the spark plug. You can see the single, black plug wire connected to the current spark plug near the front of the engine assembly. Disconnect the plug wire from the spark plug.

Connect a replacement spark plug to the plug wire. Close the engine hood and attempt to crank the tractor.

Open the hood again if the engine cranks but still does not start. Follow the plug wire to the back of the engine assembly. This will lead you to the magnetic coil. Behind the coil is the distinctly circular flywheel. The area between the two parts is the air gap. This is an very small gap that must be between 0.010- and 0.015-inch in width.

Measure the gap. If it does not fall within the specified width, loosen the magnetic coil with a wrench and reposition it slightly to the correct specification. Remeasure the air gap and ensure it is between 0.010- and 0.015-inch in width.

Close the tractor's engine cover.