Chainsaws require regularly scheduled maintenance for proper operation. Clean your chainsaw after each use and refer to your owner’s manual and these service guides before troubleshooting.

Even so, your chainsaw may need a refresh and tuning to keep it running smoothly. Follow this guide to keep your saw from bogging down.

The air filter feeds your carburetor with clean, ambient air. If your air filter is full of oil or sawdust, you can try spraying with compressed air or washing with soap and water. In the event your filter is too destroyed, replace the filter completely.

Running too-rich fuel over time can clog the metal screen in the exhaust. Remove and inspect the screen. Put the screen into a vise, and use a torch to heat and burn all of the carbon on the screen until it becomes ash. Use a wire brush to remove the ash, then replace. Inspect the spark plug for carbon soot buildup, and clean with a wire brush.

Without a fuel stabilizer, old gas accumulates moisture. If your gas is more than a month old, or has been stored between 3-6 months, drain the tank and replace with fresh fuel.

Old or poor quality gasoline along with sawdust and dirt can plug the filter in the gas tank. If your saw isn’t getting enough gas, remove and clean or replace the fuel filter.

If fuel cannot get to the carburetor, or air is sucked into a cracked line, then your saw won’t start. If you notice any of the fuel lines are looking old or developing cracks, replace the old and cracked lines with hose rated for use with fuel.

The carburetor is a mechanical computer that feeds the engine a ratio of fuel and air. If fuel sits in the system for too long, the carburetor (and the engine and fuel lines) can become sticky and clog. Remove the air filter and spray the carburetor with carb cleaner—an aerosolized acetone spray made to remove the gunk.In the event that the carburetor is too dirty or cannot be cleaned, it likely needs replacing.

Your carburetor has several adjustment screws that change how your saw performs at idle and at wide open throttle. Below are a few conditions where adjusting the screws may solve your problems. Note: chainsaw must be warmed up for 20-30 seconds before making any ‘H’ Screw adjustments.

  • If your saw has trouble idling and will die shortly after starting, then adjust the ‘L’ screw by unscrewing. This will allow more fuel through the carburetor during idle.If your saw has trouble idling and then runs lumpy with a lot of smoke, adjust the ‘L’ screw by screwing in. This will limit the amount of fuel to the carburetor at idle.If your saw idles fine, and then bogs down when pressing the throttle, then adjust your ‘H’ screw by unscrewing. This will increase the amount of fuel to the carburetor under load.If your saw idles fine, then runs lumpy with a lot of smoke when pressing the throttle, then adjust your ‘H’ screw by screwing in. This will limit the amount of fuel to the carburetor under load.

There is a small hole with a valve at the top of your gas cap which may become clogged or fail with time. Inspect, and clean or replace.

Chainsaw Hard to Start

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Chainsaw Not Starting

Carburetor Screw Adjustment by Craig Kirk