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Troubleshooting a problem with a John Deere mower is nothing more than a process to pinpoint the cause of the problem. Many times, symptoms of a problem become a distraction from finding the real reason undesirable performance exists. An example of this is an engine running poorly during operation. The engine's poor operating performance is merely the symptom of another component or system causing the problem. A restriction in the fuel filter, air filter, or water in the gas, is the true problem which troubleshooting sets out to isolate. Obviously, once the cause, or fault, is revealed, repair is possible.
Things You'll Need
1. Check the fuel for water or contamination if engine performance is poor. Prolonged storage of gasoline, or storage in humid environments, contribute to moisture build up in the gas tank. The gasoline should appear clear and bright. If contamination of the fuel is suspect, drain the fuel from the tank by removing the fuel line from the carburetor and placing into a bucket or catch-pan.
2. Inspect the fuel filter for the accumulation of dirt and debris. Despite the best efforts to keep the lawn mower fuel clean, dirt from normal operation will find its way into the gas tank. The fuel filter mounts in-line between the gas tank and carburetor. Even a small amount of dirt trapped on the filter's element is visible through the filter's clear plastic housing. Replace the fuel filter if it is suspect. A bi-annual replacement of the fuel filter regardless of its visible condition is also a good practice.
3. Clean the battery posts and terminals. The battery is the first place to start troubleshooting when experiencing starting problems. Remove the battery leads by loosening the clamps with a combination wrench. Lift the terminals off the battery posts and clean both with a wire brush. Apply a light coat of oil on the battery posts and reinstall the terminals to ensure a solid battery connection. The light oil helps to prolong future corrosion.
4. Remove the spark plug and inspect it for burns or fouling if the engine cranks but does not start. Either the engine is starving for gas, or is not getting spark from the plug to initiate engine combustion. The spark plug location can be identified by the black rubber boot with a black cable connected to it. Remove the boot and back the spark plug out with a spark plug wrench. With the plug out of the engine, examine the tip for excessive soot or the appearance of arcing. Clean the spark plug tip by lightly brushing it with a wire brush. If in doubt of the spark plug's condition, replace it with a new one of the same type.
5. Check the oil level and oil viscosity if the engine lugs when starting. Too much oil in the engine crank case builds excessive pressure in the engine. This condition will eventually effect the engine seals and create oil leaks. Keep the oil level at, or just below, the dip-stick full mark. Additionally, heavier weight oil, such as a 30 weight, may be too viscous for colder operating environments. Either of these conditions will cause an engine to lug or stall when it first starts.
6. Remove and clean the engine air filter. A clogged air filter restricts the flow of air to the carburetor and prevents fuel ignition. Three elements must exist for the John Deere engine to start and continue to run: spark from the spark plug, clean fuel, and adequate fresh air. An engine starving for air will attempt to crank, run rough, and eventually die. While some small engine air filters can be cleaned and reinstalled, replacing a dirty air filter with a new one ensures the engine remains clean on the inside, and runs smooth.
Tips & Warnings
Replace the engine air filters and engine oil once per season.
Replace spark plugs, fuel filters and drive belts every two years.
Remove the key from the lawn mower ignition while working on the engine or around the mower deck to avoid accidental starts.
Damon Hildebrand is a retired U.S. Navy veteran. He has more than 15 years within the oil and gas industry in both technical and managerial positions. Hildebrand has been a technical writer and communicator for the last four years. He is a certified specialists in lubrication and tribology, as well as a certified maintenance and reliability professional.