Here Are 14 Reasons Why a Husqvarna String Trimmer Won’t Start: FIXED IT!

The use of a string trimmer can help your yard look professionally manicured. If the engine acts up and won’t start, check for obstructions in the air intake, fuel supply, and ignition system.

A Husqvarna string trimmer won’t turn over if the air filter is clogged, the spark plug is worn out, the fuel filter is clogged, the fuel line is clogged, the carburetor is dirty, the recoil starter is broken, the fuel tank vent is clogged, the spark arrestor is clogged, or the fuel is old.

Don’t stop reading now; there are other potential causes of your starting problems besides a flooded engine.

If you need to fix your string trimmer, make sure the spark plug wire is disconnected and the machine is at rest. Read the operator’s manual that came with your Husqvarna string trimmer to learn about proper safety procedures.

Husqvarna Trimmer
Husqvarna Trimmer

Before diagnosing, repairing, or operating, make sure you’ve read and understood all of the safety instructions in the equipment’s operator’s manual. If you don’t feel confident in your ability to make the repair safely, due to a lack of knowledge, experience, or physical ability, you should get some help from a professional.

The Reasons Your Husqvarna String Trimmer Won’t Start

If you haven’t done so recently, replace the fuel filter, air filter, and spark plug when dealing with a starting problem. This will eliminate the possibility that these routine maintenance aspects are at fault.

It is recommended that these parts be replaced as part of the annual maintenance performed on your Husqvarna.

Air Filter plugged into a Husqvarna String Trimmer

The engine of your Husqvarna string trimmer can be shielded from dirt and other debris by installing an air filter.

The use of a string trimmer results in a dusty, unsanitary environment. If you don’t regularly clean or replace the air filter, it can become clogged and restrict airflow.

The lack of air prevents the engine from starting. Never attempt to complete this task without first installing an air filter on your string trimmer.

This is a potentially expensive error to make. If dirt gets into the engine’s air intake, it can cause serious problems. The string trimmer might get wrecked to the point where it needs to be replaced.

SOLUTION: Take out the air filter and wipe down the air filter housing to get rid of any dirt that is still there. If the air filter is dirty, you should get a new one.

A Faulty Spark Plug In a Husqvarna String Trimmer

Over time, carbon deposits on the spark plug make it less effective. In some cases, this can lead to a misfire in the plug and erratic starting.

A loose spark plug wire, an improper spark plug gap, and a cracked porcelain or burned electrode are some additional things to check for. Your Husqvarna may have trouble starting due to these factors as well.

SOLUTION: A dirty spark plug may be cleaned and reused if you use a wire brush on it. I’d rather get a new one. It’s a low-cost component that plays a crucial role in the string trimmer’s functionality.

Be sure the spark plug wire boot is properly attached and the gap is set according to the manufacturer’s guidelines.

Fuel Filter Plugged in a Husqvarna String Trimmer

A tiny filter is located on the fuel line that leads from the tank. This filter is installed before the fuel pump to prevent dirt and other contaminants from entering the fuel system.

Not changing the filter on a regular basis can lead to a restriction in the flow of fuel to the carburetor, which could make the engine difficult to start.

SOLUTION: Find and replace the fuel filter inside the fuel tank.

  • Before removing the fuel cap, give the area a quick wipe down to remove any dust or debris that might otherwise enter the tank.
  • Find a way to bypass the filter. An uncontaminated bent wire can be used to hook the fuel line and remove the filter from the tank.
  • The fuel filter should be taken out of the fuel line.
  • Put in the new fuel filter and fasten the fuel line to it.
  • Return the filter to its original location inside the fuel tank, then replace the cap.

A Husqvarna String Trimmer with the Wrong Fuel Mix (2-Cycle Models)

A 2-cycle Husqvarna string trimmer’s engine will seize up if you use straight gas in it. A string trimmer can be quickly destroyed by adding straight gas.

The fuel/oil ratio for a Husqvarna 2-cycle string trimmer is 50:1. Blending 50 parts gasoline with 1 part oil is called a 50:1 mix.

Husqvarna recommends using a blend of oil and gas with a minimum octane rating of 89 (mid-grade) and a maximum ethanol content of 10% in your string trimmer. Put in some ISO-L-EGD and JASO M345 FD approved premium 2-cycle oil.

Before adding it to your string trimmer, make sure to mix it in a gas can that meets safety standards. This 2-cycle oil by Kawasaki is interchangeable with XP Synthetic 2-cycle engine oil.

SOLUTION: The fuel tank must be emptied and refilled with the proper gas and oil ratio. If the problem persists, take it to a small engine mechanic so they can evaluate whether or not it can be fixed affordably.

The correct fuel for your Husqvarna string trimmer is discussed further here.

2-Cycle Premixed Fuel

Using an ethanol-free fuel mix is a great way to lessen fuel-related issues and maximize engine longevity. You can immediately fill the fuel tank of your string trimmer with this ethanol-free oil and fuel blend.

You can avoid the problems associated with ethanol that were mentioned above in the “Fuel” section. In addition, having fuel on hand is a huge time saver.

A quality 50:1 premixed fuel is produced by a number of manufacturers, including Husqvarna and TruFuel.

2-Cycle Gas to Oil Mix for Husqvarna

Mixture1 Gallon Gas2 Gallon Gas2.5 Gallon Gas
50:12.6 oz Oil5.2 oz Oil6.4 oz Oil

Husqvarna String Trimmer Wrong Gas (4-Cycle Models)

Straight gas is needed for 4-cycle Husqvarna string trimmers. To avoid damaging your vehicle, stick to unleaded fuel with an octane rating of 89 or higher and no more than 10% ethanol.

Avoid using ethanol-rich fuels at all costs. The best fuel to use is one without ethanol.

SOLUTION: The fuel tank must be emptied and the proper gas then refilled.

A Husqvarna String Trimmer With Inadequate or Incorrect Engine Oil (4-Cycle Models)

Husqvarna string trimmers powered by their 4-cycle engines have dual oil and fuel fill ports.

The engine type precludes the use of oil and fuel blends. Putting the right kind and amount of oil in your engine is crucial.

You should never operate a 4-cycle Husqvarna string trimmer with 2-cycle engine oil. To get the best performance out of your Husqvarna string trimmer, Husqvarna suggests using 10W-40 engine oil. Kawasaki makes high-quality motor oil.

The engine’s moving parts can’t function without oil. Overheating due to excessive friction is a surefire way to render your string trimmer unusable, if not completely useless.

SOLUTION: The engine oil must be changed to the proper grade. The viscosity of the trimmer’s fluid may need to be adjusted if you plan on using it in extremely cold or extremely hot weather.

If the problem persists, take it to a small engine mechanic so they can evaluate whether or not it can be fixed affordably.

Engine Oil for a Husqvarna 4-Cycle String Trimmer


In a Husqvarna String Trimmer, Use Old Fuel

Not only will stale gas restrict the trimmer’s fuel flow, but it can also corrode the carburetor and ruin the engine on a Husqvarna string trimmer. The shelf life of gasoline is about 30 days.

Ethanol, an ingredient in most gasoline, is a moisture magnet. The combination of water and ethanol causes corrosion and gumming in the fuel system.

Due to the rapid deterioration of gasoline, it is imperative that it be used within 30 days of purchase. To keep the fuel fresh for longer if you won’t be using it within that time frame, you can stabilize it with a fuel additive.

Use only unleaded gasoline with an octane rating of 89 or higher (middle grade) and no more than 10% ethanol (E10). Never put E15 or E85 in the engine; doing so will cause damage and will likely void any warranties you have on the vehicle.

SOLUTION: Remove any stale gas from your string trimmer and replace it with new gas. A 50:1 ratio of gas to fuel is necessary for a 2-cycle engine. The use of unleaded gas is necessary for a 4-cycle engine.

To prevent the fuel from going rancid and to lower the moisture content, you should add a fuel stabilizer such as Sea Foam Motor Treatment or STA-BIL.

A Faulty Primer Bulb In a Husqvarna String Trimmer

If the Husqvarna string trimmer’s primer bulb is broken and won’t fill with fuel, the machine won’t start.

SOLUTION: Inspect the primer bulb’s connection to the fuel line and tighten if necessary. A new primer bulb should be used to replace a broken fuel bulb.

A Husqvarna String Trimmer Has a Blocked Fuel Line

Sticky deposits left behind by stale fuel can impede the string trimmer’s fuel system and reduce its performance. Since this can clog the fuel line, it will prevent the engine from starting.

SOLUTION: Replace a cracked, kinked, or clogged fuel line on your Husqvarna string trimmer.

Fuel Tank Vent Plugged in a Husqvarna String Trimmer

Connected to a tube emerging from the fuel tank is the vent. If this piece gets clogged and stops functioning, the fuel tank will not receive fresh air.

Lack of venting in the fuel tank creates a vacuum that stops fuel from reaching the carburetor. The trimmer won’t turn on if the carburetor isn’t fed gas.

If you have a string trimmer that won’t start unless you remove or loosen the fuel cap, this could be a sign of a problem with the fuel tank vent.

If the trimmer starts up when the fuel cap is securely fastened, you know the fuel tank vent is not the problem. See if it turns off and won’t start again unless you loosen the fuel cap.

SOLUTION: The fuel tank vent must be replaced so that air can enter the tank.

Husqvarna String Trimmer Carburetor Clogged

The carburetor controls how much fuel is added to the air intake before it is combusted in the cylinder. Gumming up the carburetor and blocking fuel passages is a common problem with old fuel left in your trimmer.

To get your Husqvarna running again, you will need to clean or replace the carburetor.


You should be able to clean your carburetor if you have a basic understanding of mechanics. In order to thoroughly clean the carburetor, it must be disassembled and cleaned with special carburetor cleaner.

After cleaning, if the carburetor still doesn’t work, you may need to have it rebuilt or get a new one.

Depending on the age of your string trimmer and the cost of a new carburetor, you might be better off purchasing a brand-new Husqvarna model instead.

Evaluate the cost, age, and model of your current Husqvarna against those of a brand new Husqvarna string trimmer.

A Husqvarna String Trimmer Has A Bad Recoil Starter.

The recoil helps start the engine on your Husqvarna string trimmer. The inability of your recoil to function could be due to a faulty pulley, a missing or loose spring, or broken clips.

SOLUTION: Recoil spring replacement and restringing is an option.If the pulley or clips in your recoil are broken, the whole assembly should be replaced rather than trying to fix it.

A Husqvarna String Trimmer With A Plugged-in Spark Arrestor

Spark arrestors can be found in Husqvarna string trimmers that also have catalytic converters. The Husqvarna’s spark arrestor is a tiny screen designed to catch any errant sparks that could cause injury or a fire.

Blocking the vent and preventing hot exhaust air from escaping the trimmer is soot, which can accumulate on the screen. Because of this, your Husqvarna trimmer might refuse to turn on.

SOLUTION: Separate the spark plug cap. Verify that your engine temperature is not too high. Take off the hood and the exhaust cover.

Take out the spark arrestor and scrub the soot off with a wire brush. If the spark arrestor screen is too dirty to clean effectively, has a hole in it, or is otherwise damaged, it must be replaced.

Inundated Husqvarna String Trimmer

While trying to start the engine, it may have become flooded and will now refuse to turn over. This is not a major issue that requires urgent attention.

Flooding occurs in a Husqvarna engine when the choke is in the closed position and the starter rope is pulled repeatedly, allowing too much gas to enter the carburetor.

It can also occur if the primer bulb is pushed too many times or the starter rope is pulled repeatedly while the switch is off.

SOLUTION: In order to get the right fuel-to-air ratio for starting and running, “unflood” your string trimmer by following these steps.

How to Repair a Flooded Husqvarna String Trimmer Engine

  • Flip the switch from the off position to the on position. After stopping, (some) stop switches will immediately move to the run position.
  • Open the choke and let the engine run with no restriction.
  • Maintain constant pressure on the throttle trigger while repeatedly drawing the starter rope. As many as fifteen pulls may be required before it begins. The motor on your string trimmer will sputter first. Try starting it again after a few more pulls.

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