How to Repair a Gas Trimmer That Won't Start

Written by kelly nuttall
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How to Repair a Gas Trimmer That Won't Start
Small engine maintenance makes engines easy to start. (spark plug image by Yali Shi from

The most common problem with gas trimmers is that they become hard to start. Sometimes they start easily, and other times, not at all. A gas trimmer engine that starts easily is well-maintained. So when you begin to experience these problems, you know that you must step up your maintenance program. Many potential problems may prevent the engine from starting. Correct the most common issues without professional help.

Skill level:

Things you need

  • New air filter (optional)
  • Sparkplug tool
  • Cloth rags
  • New sparkplug (optional)
  • Gapping tool
  • Fuel storage container
  • 8-inch piece of wire
  • New fuel filter (optional)
  • Fresh fuel
  • Fuel stabiliser

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  1. 1

    Clean the air filter if needed. The air filter keeps dirt and debris from entering the combustion chamber. Dirty air filters block air from entering the combustion chamber. Small engines are engineered to require the correct air/fuel ratio before they will start.

  2. 2

    Disconnect the sparkplug wire from the spark plug. Unscrew the sparkplug with a sparkplug tool. Replace the sparkplug if it is more than one or two seasons old. If the sparkplug is relatively new, inspect it for damage or wear. Wipe the electrode end of the plug off with a cloth rag. If, after wiping the sparkplug clean, you see it is in good shape, check the gap with a gapping tool (the gap should be between 0.020 and 0.032 inches, depending on the make and model of the trimmer) and reinstall the sparkplug. If the plug is damaged, replace it. Reinstall the plug and reattach the sparkplug wire.

  3. 3

    Empty the fuel tank into an approved fuel storage container. Bend an 8-inch piece of metal wire into a hook and insert it into the empty fuel tank. Pull the tube with the fuel filter attached to the end out of the tank. Inspect it and clean it with a nonflammable solvent. Reinstall it if it is not damaged. If it looks damaged or excessively dirty when it is pulled out of the fuel tank, replace it.

  4. 4

    Add fresh, stabilised fuel to the tank. Stale fuel will not allow that engine to start very easily. Fuel expires in 30 to 90 days if it is not stabilised with a stabiliser additive, which helps it last up to a year. Attempt to start the engine. If it does not start, take the trimmer to your local service dealer.

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