How to Troubleshoot a John Deere 335 That Is Backfiring

The John Deere 335 Garden Tractor is a riding lawn mower designed primarily for residential use, although the device is capable of being equipped with attachments that make it a viable option for commercial use as well. This lawn mower is powered by a two-cylinder Kawasaki engine that generates 20 horsepower. Despite John Deere's reputation for building reliable products, the spark plugs included may wear down over time and cause the engine to backfire. Knowing how to diagnose and fix this problem is important.

Instructions

- 1
  Open the hood of the tractor and locate the spark plug housing. It is usually situated on the left side of the engine, next to the air intake screen.
- 2
  Disconnect the wiring on both sides of the spark plug and remove the plug.
- 3
  Clean the spark plug with a wire brush.
- 4
  Inspect the spark plug for cracks. Examine the electrodes for damage; damaged electrodes will need to be replaced. Look for any other signs of wear and tear, such as melting in the center of the spark plug, bent sparks and oil buildup in and around the shell of the spark plugs. Purchase a new spark plug if any cracks or damage are found.
- 5
  If the engine continues to backfire, purchase and install a new spark plug.

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