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8 Reasons a Husqvarna Leaf Blower Runs ROUGH

A Husqvarna leaf blower will begin to run rough due to a dirty carburetor, plugged fuel filter, clogged fuel line, bad fuel tank cap, plugged air filter, dirty spark plug, plugged spark arrestor, or old fuel.

Always shut off the blower, remove the spark plug boot, and wait for all parts to stop moving. Take care when working around the hot engine and muffler. It’s best to allow them to cool off to avoid injury.

Husqvarna blower runs rough

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Follow all safety instructions provided in your equipment operator’s manual before 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.

8 Reasons Your Husqvarna Leaf Blower is Running Rough

1. Old or Bad Fuel

Gas can go bad pretty quickly. This can cause component failure and fuel restrictions when old gas is left to sit in the leaf blower for long periods of time

Most gasoline contains ethanol that is produced from plants to make fuel more environmentally friendly. While a little ethanol is okay to use in most vehicles, it is not good for the small engine in your Husqvarna leaf blower.

Ethanol attracts moisture to the fuel system which can leave behind varnish and gummy deposits that clog the fuel system and prevent the carburetor from functioning correctly. Because of this, don’t use gas that contains more than 10% ethanol.

Husqvarna 2-cycle leaf blowers require gas and oil mixed at a ratio of 50:1. 50 parts gas is mixed with 1 part oil. Refer to this guide on fuel for Husqvarna leaf blowers to get measurements to mix the fuel correctly.

  • Use unleaded gasoline with a minimum 89-octane rating and a maximum ethanol content of 10%. The less ethanol in the gasoline, the better.
  • Mix in 2-cycle engine oil like Husqvarna XP oil.

It is best to purchase fresh gas and use it within 30 days. If you are unable to use a tank of fuel this quickly, add a fuel additive like Sea Foam to stabilize it and reduce the negative effects of the gas.

2. Dirty Spark Plug

Spark is required to ignite the fuel and air mixture for combustion. A dirty or damaged plug can cause the spark plug to fire intermittently potentially causing the blower to run rough and sluggish.

In addition to a dirty spark plug, the electrode gap could be wrong or the spark plug boot could be loose resulting in poor engine performance.

Remove the spark plug using a spark plug wrench. Check its condition. Replace the spark plug if you find the tip is very dark in appearance, the porcelain is cracked or the electrode is burnt.

If you find your spark plug is just dirty, clean it with a wire brush or replace it with a new spark plug.

I prefer to use a new spark plug since it is a crucial component to having a leaf blower operating at its best. Make sure you have a properly gapped spark plug using a feeler gauge.

Install the new or clean spark plug and securely attach the spark plug wire.

3. Plugged Fuel Filter

The fuel filter attaches to the end of the fuel line and sits in the fuel tank. Fuel is filtered to prevent dirt and debris from entering the fuel system.

When the filter becomes clogged so a good steady flow of fuel isn’t able to pass through the filter, the blower will begin to run rough because it isn’t getting sufficient fuel.

A plugged fuel filter must be replaced. Set the leaf blower on a flat surface, and remove the fuel tank cap. Pull the fuel filter out of the tank.

You may want to use a clean bent wire to hook around the fuel line and pull the filter out of the tank. Holding the fuel line and ring clip in one hand, securely grab the filter and pull it out of the fuel line.

Securely attach a new Husqvarna fuel filter. Place the fuel filter back inside the fuel tank. It must be placed so it sits in the fuel even when the fuel level is low. If it isn’t, the leaf blower won’t get fuel to run.

4. Clogged Fuel Line

Old fuel can clog the leaf blower’s fuel line restricting fuel flow. Look for a clogged line or a line that may have gotten pinched or kinked. Replace any damaged or clogged fuel line with a new fuel line.

5. Bad Fuel Tank Cap

The fuel tank vent can become plugged or damaged preventing air from passing through the vent to equalize the air pressure in the fuel tank. A plugged vent can cause a vacuum to form in the fuel tank. This keeps fuel from flowing out of the tank.

You can test this by loosening or removing the blower’s fuel cap to allow air into the tank. Start the blower, and allow it to run.

Be careful and keep your leaf blower level so you don’t spill any gas from the tank. If the blower runs strong and doesn’t bog down and run rough, tighten the fuel cap and see if you can replicate the issue to confirm the fuel tank vent is the problem.

Replace the fuel tank vent if your blower starts to act up and run rough again after installing the fuel cap. Most vents on Husqvarna leaf blowers are built into the fuel cap and you should replace the fuel cap assembly.

6. Plugged Air Filter

The engine requires air to run. Without enough air, the leaf blower will run sluggish and rough.

One of the items that can restrict airflow is a plugged air filter. The air filter can become plugged from dirt and debris when not regularly cleaned and changed.

If you find your air filter is plugged, I recommend replacing the filter. The small air filter is usually not very expensive. It is an important component when it comes to protecting the engine.

Because there are so many different types of filters used on a Husqvarna leaf blower, refer to your operator’s manual for steps to clean the style of air filter in your leaf blower.

Below I have listed cleaning instructions for a few common types of Husqvarna air filters.

  • Clean a Husqvarna blower fiber air filter:
    • Clean it by removing it from the housing and brushing off the dirt.
    • You can also wash it in a mild dish soap and water solution. Rinse until the water runs clear and lay flat to dry.
    • Before reinstalling, wipe out any dirt from the air filter housing and cover.
    • Replace a filter that is damaged or very dirty.
  • Clean a Husqvarna foam primary filter:
    • Remove the foam filter from the air filter housing.
    • Wipe out any dirt remaining in the housing and cover. Don’t allow dirt to fall into the air intake.
    • Wash the foam filter in a solution of warm water and mild dish detergent.
    • Rinse until the water runs clear. Ring the water out of the filter and lay it flat to dry.
    • Once dry, cover the filter with engine oil and squeeze out any excess oil. You don’t want it to be dripping with oil. (Only add oil to foam filters that are used as the main filter. If your filter is a pre-filter used in combination with a paper air filter, do not add oil. This will damage the paper filter).
    • Install the foam air filter.
    • Reattach the air filter cover.
  • Clean a Husqvarna backpack blower paper air filter & foam pre-filter:
    • Remove the pre-filter and air filter from the housing.
    • Wipe out any dirt remaining in the air filter housing and cover. Don’t allow dirt to fall into the air intake.
    • Clean the foam pre-filter by washing it in a mild dish detergent and water solution.
    • Rinse until the water runs clear. Ring the water out of the filter and lay it flat to dry.
    • Inspect the paper air filter. If it is dirty, replace it with a new one. If it is not, you can reuse it.
    • Install the air filter and dry the pre-filter.
    • Reattach the air filter cover.

7. Dirty Carburetor

The carburetor mixes the correct proportion of air and fuel needed for your leaf blower to perform at its best. The passageways can become clogged and the small components can fail to function correctly.

This can cause an insufficient amount of fuel mixed with air resulting in a rough running leaf blower.

You may be able to clean your carburetor to get it working again. You may end up having to rebuild (if rebuild kits are available for your carburetor) or replace the carburetor if cleaning doesn’t help.

8. Plugged Spark Arrestor

There is a small metal screen that keeps hot exhaust material from shooting out of the leaf blower causing injury or starting a fire. This screen is a spark arrestor.

It will become plugged with a carbon buildup that will affect how the engine runs when it isn’t kept clean.

Disconnect the spark plug wire. Remove the engine exhaust cover. Carefully remove the spark arrestor screen. Clean the screen with a metal brush and reinstall it. Reattach the engine exhaust cover. Reattach the spark plug wire.

If the screen isn’t able to be sufficiently cleaned or you find it is damaged or has a hole in it, replace it with a new spark arrestor screen.