Why Does My Chainsaw Keep Stalling?

Notice when the engine quits

A brief run gives you a different clue from a saw that quits only when you turn it. We’d check the fuel before removing a filter, because a low tank or old mix can explain that brief run. Notice when the engine quits, and keep your model’s owner’s manual beside you as you move through the checks.

Check the fuel level

Look at the fuel level first. A gas saw without enough fuel may fire, run briefly and stop. If the tank is low, refill it with the mix specified for your saw before moving on to the filters.

Replace a questionable mix

Fuel that has sat for weeks or months can lose effectiveness and clog the fuel system. If the fuel’s quality or mix is in doubt, empty the tank and replace it with a known, correct mix for your machine. Follow your model’s instructions for that mix instead of choosing a ratio from another saw.

On a STIHL saw, keep the refueling spot at least ten feet from where you’ll use the saw. That separation belongs with every refill, including one made just to rule out questionable fuel.

Look for air-filter buildup

A dirty air filter can restrict the air reaching a gas engine and leave the saw sputtering or unable to keep running. Use your model’s manual to locate the filter and check it for buildup. Clean or replace it as those instructions direct.

On Husqvarna saws with a filter that can be washed, remove it, use warm, soapy water and let it dry completely before reinstalling it. Replace a damaged or very dirty filter. A blocked filter may also call for replacement, so use your model’s filter instructions to choose the right treatment.

Check the exhaust screen

The spark arrestor is a small screen at the exhaust. A clogged one can make a gas saw stall. If your saw has a screen, use its manual to find and check it. On a Husqvarna saw, where the screen can be removed for cleaning, take it out carefully and use a soft brush.

If the screen is clean and the stall remains, check fuel delivery next. The in-tank filter can be blocked even when the tank holds a fresh mix.

Inspect the in-tank filter

Use your model’s manual to check the in-tank fuel filter for blockage and the pickup and hose for blockage or cracks. The filter feeds fuel from the tank while keeping debris out of the supply. Replace a filter that is blocked or damaged.

For a filter your manual directs you to replace, pull out only enough fuel line to expose it. Don’t pull the line hard. Remove the old filter, fit the new one and feed it back into the tank, leaving the line in place.

A stall when you tilt the saw

On a Husqvarna chainsaw, starting and then dying can have more than one cause. If turning the saw changes the stall, the in-tank pickup is a useful next check. Its weighted filter and flexible line are designed to move with the fuel so the filter stays submerged as the saw tilts.

Check whether the filter is present and sound, and look for a damaged or incorrect line or a leak. Those faults can interrupt fuel flow as the saw changes position.

If the outside checks don’t settle it

Low compression can also leave a gas saw weak or unable to keep running. On a Husqvarna saw, a preliminary check is to place it on the ground and carefully try to lift its weight by the starter cord. A cord that stays taut is the expected result; one that slowly extends points to compression that needs a more precise check.

An air leak at a crankshaft seal or damage to a piston or its rings can be involved. If the cord extends, or the fuel, filter and screen checks leave the saw stalling, take it to a servicing dealer for evaluation. Tell them when it quits and what you found. Have a professional handle any check you’re uncomfortable doing.

Keep the next tank ready

Keep the next fuel check straightforward by knowing how old the mix is in both the can and the tank. On a STIHL saw, never store or use mix older than 60 days in either place. When the saw is used again under its own operating instructions, the result you’re looking for is an engine that stays running at the point where it used to quit.