How to Troubleshoot a John Deere 120
- 1). Change the fuel if the engine is sputtering and performing poorly. Gasoline stored for a long time in a tank has a tendency to lose its chemical properties and effectiveness. Depress the brake pedal and restart the engine.
- 2). Examine the spark plugs and their wires. Make sure everything is properly connected if the engine stalls out or fails to start completely. If the spark plug appears black as a result of being burned out, it may need to be changed. The fuel filter may be dirty as well and should be changed if you have operated the lawn tractor for more than one year.
- 3). Clean the cooling fins if the tractor begins to overheat. When you mow grass a lot, dirt and debris gets kicked up occasionally. This can clog the radiator fins located in the front of the tractor. Use a garden hose to clean the front of the cooling fins. Do not use high velocity, as doing so could damage the fins. Check the oil levels as well; bad oil or no oil in the tractor can cause engine and overheating problems.
- 4). Check the mower blades. If they are not cutting the grass properly, it is time to have them sharpened by a professional. Occasionally, dull or improperly balanced blades will cause the L120 tractor to vibrate. This will usually happen when mowing uneven and bumpy surfaces that can sometimes disrupt the tractor's calibration settings. Try not to mow too fast; you must allow the blades to cut the grass on their own. Too much speed can jam the mower and provide for an uneven cut.
Source...