Chainsaw Keeps Stalling. Tips from a Professional:


Chainsaws usually stall when the engine is getting either too much or too little gas from the carburetor. A stalling chainsaw could start normally and die out after a few minutes or even be difficult to start. Some common issues that cause a chainsaw to stall are gas issues, carburetor problems, clogged fuel lines, etc. In this blog post, I will show you how to fix these issues yourself.

Chainsaw keeps stalling:

Usually, chainsaw stalls when its engine is not receiving the adequate amount of gas to keep it running. This can be too much or too little gas. A failing carburetor is the most common reason behind a stalling chainsaw. But a dirty fuel filter, clogged gas lines, faulty spark plug are also a few of the common reasons why your chainsaw may stall.

Here’s a quick summary of things you should do if your chainsaw keeps stalling:

  • Clean/replace the air filter: Debris buildup in the air filter can starve the engine. So, start the procedure by cleaning the air filter or replace it if it is too dirty or damaged.
  • Fix/replace the fuel filter: A dirty fuel filter blocks the gas flow from the tank into the lines, and a damaged filter causes the fuel lines to be clogged. Check the fuel filter and clean, repair, or replace it as necessary.
  • Fix the spark plug: A carbon, debris, or oil buildup on the spark plug’s insulator nose can cause the engine to stall. Check and clean the spark plug.
  • Fix the carburetor: Clean and/or adjust the carburetor to ensure that the engine gets the correct amount of gas.
  • Fix the fuel lines: Unclog the fuel lines using a cleaning liquid blended with gas or replace the fuel lines if they are too faulty to be fixed.
  • Fresh gas: Drain out the old gas from the gas tank and add fresh gas, preferably blended with a small quantity of a fuel stabilizer.

In this blog post, I will look into the different reasons in more detail and show how to fix the stalling problem.

Fixing a Chainsaw that Won’t Stay Running/Keeps Stalling:

Sometimes a chainsaw will start but fail to stay running. When a chainsaw continues dying minutes after starting, it is stalling. A stalling chainsaw is when the engine isn’t getting enough energy to stay running. This happens when the gas supply to the engine is interrupted. To fix this, all components of the chainsaw involved in the gas delivery have to be checked.

The most important of these components is the carburetor. It gets air and gas, creates the correct air-gas mixture, and provides it to its combustion chamber.

Other components that take part in gas delivery include fuel filters and fuel lines. Additionally, the air filter and spark plug can be the reason for the stalling problem.

Here is how to check and fix these individual components:

● Air Filter:

A chainsaw’s air filter stops dirt and debris from entering the engine with the incoming air. This blocked debris can pile up and clog the filter, preventing fresh air from reaching the engine. If you regularly clean your chainsaw’s air filter, the engine will get an adequate supply of fresh air, preventing it from stalling.

Cleaning the filter is quite easy, although it is well protected and not exposed to the environment directly. The best way to know the air filter’s location is from the slits at your saw’s surface that is there to ensure a free airflow in and out of the chainsaw.

In extreme cases of debris buildup, the slits may become covered from the inside by particulate matter. Which is a danger to your chainsaw’s service life.

Once you know the air filter’s location, remove its outer covering using a screwdriver. Remove the main filter cover under the outer covering. Removing the main cover with a screwdriver will give you access to the air filter. Remove the filter from your chainsaw gently.

If your chainsaw has a foam filter, you can clean it with water. You need two buckets of water and a hand bristle brush. A toothbrush will also work. Put some soap in a bucket filled with hot water and swirl it to create foam. Take the filter, gently scrub it with the brush to loosen the dirt particles. Then dip it in the hot water bucket.

Swirl it in the water to let the soap absorb and pull out its dirt. After a few minutes in hot water, remove it and dip it in a cold water bucket to remove the dirt particles not taken out by the hot water. Take it out from the cold water bucket after some minutes and give it enough time to dry completely.

Suppose the foam air filter is extremely dirty or damaged. Replace it. If your chainsaw uses a paper air filter, it can not be cleaned. It needs to be replaced.

It would be best to clean the covers since the incoming air has to pass through the covers first. To clean the covers, dip them one by one in the hot water bucket, scrub them gently with the brush then rinse with cold water. Leave them for some time to dry.

Once the filter and covers have dried completely, reinstall them in their correct positions. Start with the filter, then the inner cover, and then the outer cover locking each in place using a screwdriver.

● Fuel Filter:

The fuel filter in a chainsaw is usually found inside the gas tank at the end of the fuel line. A fuel filter is there to prevent dirt or debris from entering the fuel line. When your chainsaw’s fuel filter becomes damaged, debris from the gas tank enters the fuel lines. There it can cause a clog and preventing the engine from receiving a sufficient amount of fuel. Causing it to stall.

If your engine is stalling, check the fuel filter for damage or clogging. If needed, replace it with a new one. Consult your chainsaw user manual on how to remove the damaged fuel filter and install its replacement correctly. Fuel filters can be found easily and are relatively inexpensive.

● Spark Plug:

A faulty spark plug can cause your chainsaw to stall. A troubled spark plug can be spotted when the insulator nose of the electrode is covered with a carbon deposit, oil, or gas. When the tip of a spark plug becomes covered, it causes the voltage to flow along with the insulator nose and back into the metal shell and ground out instead of connecting the gap between the two electrodes to fire normally.

An inaccurately adjusted carburetor usually results in a rich fuel mixture which causes spark plug fouling. I recommend replacing your chainsaw’s if it is not in great shape. You can also try to clean the spark plug’s firing tip using a metal brush or sandpaper.

● Carburetor:

The most common reason behind a stalling engine is a dirty or wrongly adjusted carburetor. A faulty carburetor fails to supply the correct air-fuel mixture to the engine. And can cause the engine to stall. If you have checked and fixed the components discussed above, but your chainsaw is still stalling. The next thing you should do is clean and adjust the carburetor.

– Cleaning the carburetor:

You can follow these simple steps to clean your chainsaw’s carburetor:

  • Step 1: Clean the intake components: Use a cleaner spray to clean the carburetor’s intake components of a gummy residue that builds up because of bad gasoline.
  • Step 2: Wash the needle valves: A carburetor’s needle valves often get clogged because of propane deposits. Wash the needle valves with a carburetor cleaning liquid, gently scrubbing with a toothbrush. Let the needle valves dry before proceeding.
  • Step 3: Use the pull cord: Blend the gas in the tank with a cleanser and pull the cord several times with intermediate pauses. Even though your chainsaw won’t be running during this process. Pulling the cord will cause some of the fuel-cleanser mixture to flow through the carburetor. And wipe off the gummy residue clogging it.
  • Step 4: Add fresh gas: Drain old/stored gas and add fresh gas. If you plan to store your chainsaw for more than a month. I recommend adding some fuel stabilizer to the gas tank and other stored gas. Start the chainsaw so it can reach the carburetor as well.

The above procedure is effective enough if your chainsaw carburetor is mildly dirty. If the carburetor’s internal components are too clogged and too dirty. You will have to disassemble it and wash the individual components. You can use a carburetor cleaner liquid and a toothbrush for this. Dry the components using a clean cloth before assembling them again.

– Adjusting the carburetor:

Most chainsaw carburetors are equipped with three adjustment screws:

  • Idle speed/throttle adjustment: This adjustment controls how much the throttle valve will stay open when the throttle trigger is released. If the throttle adjustment is too low, the engine dies as soon as the throttle trigger is released. On the other hand, if the throttle adjustment is too high, the high idle speed will engage the centrifugal clutch and cause the chain to run, a dangerous situation that can cause serious damage.
  • Low-Speed Fuel Adjustment: This adjustment controls the fuel proportion in the combustible air-fuel mixture at idle speed. If this adjustment is too rich, the engine will load up and die at idle speed. On the other hand, if the air-fuel mixture is too lean, the engine starves. If this adjustment is too lean, it will cause the engine to die out. This adjustment is marked as “L” on the carburetor.
  • High-Speed Fuel Adjustment: This adjustment controls the gas proportion in the combustible air-fuel mixture when the chainsaw is operating at cutting speed. If this adjustment is too rich, it will prevent your chainsaw from reaching the RPM level required for it to reach maximum power. It will also result in sluggish throttle response and cause smoking and performance loss. If the mixture is too lean, it will cause the engine to reach an RPM level, likely to cause cylinder seizure and bearing failure. Also, the cutting power will decrease. This adjustment is marked as “H” on the carburetor.

Procedure for adjusting your chainsaw’s carburetor:

Once you have fixed the air filter and added fresh gas to at least half the capacity, you can proceed to carburetor adjustment by balancing the high and low-speed screws. To adjust the carburetor, ensure that the high and low-speed screws are completely turned in as soon as your chainsaw becomes warm.

Turn each screw to the left in one full turn, or gradually, depending on the manufacturer’s provided manual. After that, turn the high-speed screw clockwise to make the mixture lean. Finally, turn the high-speed screw counterclockwise until you hear flutter. In this setting, you have achieved the right RPM for your chainsaw.

You may also use the throttle to perform a quick adjustment/test. To do this, ensure that your chainsaw is on idle and that the chain is not moving. If the chain is turning, gradually turn the throttle screw counterclockwise until the chain stops turning.

● Fresh Gas:

Gas that sits in the tank for more than 1 or 2 months can partly evaporate and produce a sticky residue that can clog the carburetor and fuel lines. You should never store gas in your chainsaw’s gas tank for an extended period. I recommend using fresh gas each time you use your chainsaw to ensure the best performance and maximum service life.

Alternatively, you can add some fuel stabilizers to the gas tank and other stored gas. After adding, start the chainsaw shortly. So the stabilizer can reach the carburetor as well.

Chainsaw Dies When you give it gas:

Suppose your chainsaw dies when you give it gas. Or at full throttle. It is mostly because of the earlier mentioned reasons. To get it back to its original performance, check each of the discussed parts. And fix them where needed.

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