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9 Reasons Your Husqvarna Chainsaw Loses Power

When your chainsaw loses power, it will not be able to perform at its best. It won’t run at full RPMs and will have difficulty cutting through wood. Your cutting task will become increasingly frustrating when you don’t find and fix the problem.

A Husqvarna chainsaw loses power when the engine receives intermittent spark, reduced airflow, or restricted fuel flow. This can be a result of a dirty spark plug, plugged air filter, clogged spark arrestor, plugged fuel filter, clogged fuel lines, or a dirty carburetor. Your carburetor may also need an adjustment.

Keep reading and I’ll explain more about why your Husqvarna may be losing power. Follow all safety precautions before performing repairs including removing the spark plug wire and waiting for all moving parts to stop.

Reasons a Husqvarna Chainsaw Loses Power:

  • Plugged air filter
  • Clogged spark arrestor
  • Plugged fuel filter
  • Clogged or punctured fuel line
  • Old fuel
  • Dirty carburetor
  • Carburetor needs an adjustment
  • Dirty spark plug
  • Chain brake engaged
Husqvarna chainsaw loses power

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Follow all safety instructions provided in your equipment operator’s manual prior to diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.

Lack of Air Causes a Husqvarna Chainsaw to Lose Power

A good supply of air is required to keep the chainsaw running. When looking for a reason the saw loses power, check for items that can restrict airflow like a plugged air filter and clogged spark arrestor.

Plugged Air Filter in a Husqvarna Chainsaw

A clean air filter is a necessary component to have installed on your chainsaw. This filter keeps dirt and debris from entering the carburetor throat to prevent damage and wearing of the engine.

When using your Husqvarna chainsaw, you are creating some very dirty conditions. Airflow can become restricted when the air filter becomes plugged with dirt and debris because it isn’t being cleaned or replaced regularly.

A plugged air filter will cause a loss of power. When you experience this, check the filter. Clean it or replace it if necessary. Never run your chainsaw without an air filter. Doing this can result in significant engine damage.

How to clean a Husqvarna chainsaw air filter:

  • Remove the engine cover.
  • Remove the air filter.
  • Wipe out any dirt from the air filter housing.
  • Brush dirt from the filter or shake it to remove the dirt.
  • If needed, wash it in a mild dish detergent and water solution, rinse until the water runs clear, and allow the filter to completely dry.
  • Reinstall the clean filter. Purchase and install a new air filter if the old filter is extremely dirty, damaged, or is unable to seal properly.

Clogged Spark Arrestor on a Husqvarna Chainsaw

You will find a spark arrestor on many Husqvarna chainsaws. This is a small mesh screen installed to prevent hot exhaust material from leaving the muffler.

When the screen becomes plugged with carbon buildup, you may experience a loss of power where the Husqvarna chainsaw won’t run at full RPMs. This is because the engine isn’t able to exhaust sufficiently.

This screen should be checked often and cleaned to prevent buildup. To do this, first, disconnect the spark plug wire and allow the muffler to cool.

Carefully remove the spark arrestor screen. Clean it using a metal brush. If you find any damage or holes in the screen, replace it with a new spark arrestor screen.

Reattach the engine exhaust cover and engine cover once you have installed a new or clean spark arrestor. Reattach the spark plug wire if you are done performing all repairs and maintenance.

Lack of Fuel Causes a Husqvarna Chainsaw to Lose Power

Your Husqvarna will begin losing power when there is a lack of fuel in the engine. This can be due to fuel restrictions caused by a plugged fuel filter, plugged fuel line, or dirty carburetor. The carburetor may only need an adjustment to fix the amount of fuel mixed with air.

Begin by checking the fuel supply to ensure it is fresh. If it is old, fill it with fresh fuel. You can find more information on fuel to use in your Husqvarna chainsaw here.

Plugged Fuel Filter on a Husqvarna Chainsaw

The fuel filter is attached to the end of the fuel line to strain the fuel as it comes out of the fuel tank. Its purpose is to keep dirt and debris from entering the fuel system.

When the fuel filter is not changed out regularly or you are using very dirty fuel, it can become plugged keeping a sufficient amount of fuel from flowing through the filter. This lack of fuel flow will cause a Husqvarna chainsaw to lose power.

Clogged or Punctured Fuel Line on a Husqvarna Chainsaw

Old fuel sitting in the chainsaw is likely to leave behind varnish and sticky deposits that clog the fuel line. This can restrict fuel flow.

When you find there is a clog in the fuel line, remove the fuel line and clean it to remove the clog using carburetor cleaner. Spray the carburetor cleaner into the line to loosen the clog. Then blow compressed air through it to remove the clog.

Repeat spraying the cleaner and blowing compressed air until the line is free of the blockage. Replace with a new line when you find it is dry or cracked.

Another thing to look for is a punctured fuel line. A punctured line can introduce air into the fuel system. Additional air to the cylinder can make your Husqvarna lose power when there is no longer a correct mixture of fuel and air.

Dirty Carburetor on a Husqvarna Chainsaw

The carburetor mixes the correct proportion of air and fuel required for your Husqvarna chainsaw to start and continue to run. The passageways can become clogged and the small components can fail to function correctly which can be the reason the chainsaw stops running.

Old fuel is a big reason why a Husqvarna carburetor will stop working. You may be able to clean or rebuild your carburetor to get it working again. You will have to replace the carburetor if this doesn’t work.

Carburetor Needs Adjustment on a Husqvarna Chainsaw

The carburetor may need to be adjusted to change the RPMs at idle speed and at full throttle. There are adjustment screws on the carburetor to make these adjustments.

The screws are labeled “L” for low speed and “H” for high speed. Let the chainsaw idle and adjust the low-speed screw clockwise and counter-clockwise until you find the “sweet spot” where it runs smoothly and not sluggish.

Next, adjust the “H” to get a good smooth RPM at full throttle. Don’t over-adjust and allow the RPMs to increase too much or you will damage the engine.

Husqvarna does have some limits to the adjustments you can perform to the carburetor. If you are having problems with the carburetor, bring your chainsaw to your local Husqvarna dealer.

A special tool may be required so only your dealer can make the necessary adjustments.

Lack of Spark Causes a Husqvarna Chainsaw to Lose Power

Spark is required to ignite the fuel and air mixture to form a combustion in the cylinder so the chainsaw will continue to run. When the Husqvarna chainsaw isn’t getting consistent spark, it will bog down and lose power.

Dirty Spark Plug in a Husqvarna Chainsaw

The spark plug is a wear item. It must be replaced regularly. I recommend replacing it once a year for casual usage. However, if you are using your chainsaw often, you may need to change it quarterly to ensure you are running a good plug.

The spark plug will become dirty over time causing an intermittent spark and a loss of power. Remove the spark plug and inspect the tip. If it is dirty, but not very dark in color, you can try to clean it using a wire brush.

If you find the spark plug is very dark in color; has broken porcelain or burnt electrode, you must replace it with a new one.

Before installing a new spark plug, check that the spark plug gap is correct. Install the plug and securely attach the spark plug wire. An incorrect gap or a loose wire can cause the chainsaw to bog down and lose power.

Other Item That Causes a Husqvarna Chainsaw to Lose Power

Chain Brake is Engaged on a Husqvarna Chainsaw

The chain brake is a plastic handle that sits in front of the regular handle you use to hold the chainsaw. This is a safety feature installed to protect the user when the saw kicks back.

When the chain brake is engaged, the chainsaw will bog down losing power. Check the chain brake and make sure it is in the off position.