Before Troubleshooting

• 1). Undo the screw holding the air filter cover in place over the rear of the engine. Lift the foam pad from the filter box. Wash the filter in the warm, soapy water, allowing it to dry completely before reinstalling it. Replace the filter if washing it doesn't clean it.
  
  
• 2). Unscrew the muffler cover's two bolts and remove the front of the muffler. Free the spark arrestor screen from inside the muffler. Wash the arrestor screen with the soapy water and scrub it with the brush. Wipe it dry with the rag. Scrub the inside of the muffler and the exhaust port at the rear of the muffler with the brush. Replace the muffler if carbon deposits cannot be cleaned.
  
  
• 3). Drain any old fuel still left in the tank from the last use into the fuel container. Pour in about 2 tsp. of clean gasoline, close the cover and swish the gas around in the tank for ten seconds. Drain the gas into the container. Scrub the inner walls of the tank with the brush and rag. Inspect the fuel filter, on the tip of the fuel line, for any clogs. Fill the tank with freshly mixed trimmer fuel.
  
  
• 4). Loosen the boot on the spark plug's tip. Undo the plug with the socket wrench. Replace the plug with a new one (cleaning and checking the gap on an old plug is more difficult than replacing it). Check the inside of the boot for any debris. Check the wire to make sure it isn't damaged.
  
  

Troubleshooting

• 1). Insert the new spark plug into the boot, metal tip pointing out. Hold the rubber boot, wearing leather gloves, about 2 cm from a grounded metal point on the engine's frame. Pull the start rope four times and look for a blue spark. If a spark is present move on to the next troubleshooting test; but if there's no spark, or it's a weak yellow, your ignition module probably needs replacing, which a professional should perform due to the dangerous current involved.
  
  
• 2). Try pulling the starter rope out: it should be neither too hard nor too easy to pull. If it's too hard you may have a sheared flywheel key, which a professional needs to fix since the air gap between the magnets must be set properly. If it's too easy, hold the trimmer up in the air by the starter rope. If the rope pulls out under the weight, the compression is low or the recoil spring is damaged. You can replace the recoil spring yourself, but compression problems usually mean serious engine problems as air is leaking somewhere inside the cylinder.
  
  
• 3). Remove the air filter cover again and set the engine's choke to the halfway setting. Try starting the trimmer and as soon as the engine fires squirt a one-second shot of the carburetor cleaner directly into the open choke. If the engine dies and won't start again, you will need to have a professional clean and service your carburetor. If it runs or fires up again, let the smoke burn off: you will need to clean your carburetor soon.