Husqvarna 125b Blower Only Runs on Choke – Fixed

If you live in an area where leaf storms are a norm, your 125bv is no less than essential for you, and you need your essentials to work smoothly!

If your Husqvarna 125bv Blower runs only on full choke, it is most likely because of a clogged carburetor, fuel cap, breather valve, or fuel filter. Other reasons may be a damaged fuel line, carburetor gasket, an unadjusted carburetor, or old gas.

Identifying the issue is only the first hurdle; we’ll try to help you reach the finish line by aiding you in solving the issue.

Before we dive into the troubleshooting bit, it is essential to answer a few questions, like “what does a choke do?”, “Is this even an issue that you should be worried about?”

What Does a Choke Do?

The primary function of a choke is to draw extra fuel into the carburetor and make a cold engine easier to start up. If your leaf blower requires extra fuel, the air-fuel mixture is out of balance.

What is essential to understand is that a warm leaf blower must start quickly and ideally without a choke. However, if it won’t operate at all without the choke on, there must be a problem, more often than not- with the carburetor.

Understanding a Leaf Blower Fuel System

  1. You add fuel to the fuel tank.
  2. Then the fuel flows through the fuel filter (cleansing check) and into the carburetor.
  3. The carburetor mixes the fuel with air and passes the mixture to the combustion chamber

The carburetor is designed to maintain the right level of air-fuel mixture for the leaf blower to run without any problems.

Any errors in the process mentioned above may lead to your leaf-blower malfunctioning, therefore becoming dependent on the choke to operate.

Potential Problems and Solutions to a Husqvarna 125bv That Only Runs on Choke

1) A Blocked Fuel Cap or Breather Valve

Peek at the top of the fuel tank- you’ll spot a fuel cap that has a breather valve. This valve allows air to enter the tank as the fuel is used away.

If this breather valve is clogged, a second vacuum is created inside the fuel tank, which draws the present fuel away from its rightful destination and as a result, there is a vacuum in the carburetor.

This will cause the fuel to no longer pass through the filter and into the carburetor and engine, and the blower will depend on the choke and its strong pistol movements to pull fuel into the carburetor.

Running Diagnostics

To check whether this is the issue preventing your leaf blower from functioning without the choke, use these two methods to run diagnostics –

  1. Allow your Husqvarna 125bv Blower to run for a few moments on choke. Then, gently remove the fuel cap and listen carefully. The air rushing into the fuel tank indicates the breather valve is clogged. (This above method requires you to be present in a place with no noise other than that of the blower.)
  2. Loosen or remove the fuel cap before boosting up your leaf blower. If you hear air gushing into the fuel tank then the breather valve is blocked


The solution to a blocked breather valve or a clogged fuel cap is easy- replace them with new ones!

2) A Clogged Fuel Filter

An unbalanced air-fuel mixture will lead to the leaf-blower malfunctioning! What does a clogged fuel filter do? It stops fuel from flowing into the carburetor.

A lower amount of fuel than air in the carburetor will result in an unbalance- and this is where all the troubles begin. (Which is temporarily solved by opening the choke)

Now, some of you may be wondering. Even if we engage the choke, how will it pull fuel through the clogged fuel filter?

When the choke is started, it shuts the carburetor’s exhaust gap and allows the engine piston air vacuum to develop into a stronger one. This results in a stronger pull on the fuel passing through the fuel filter- just enough for the engine to run!

Running Diagnostics

Remove the fuel filter from your Husqvarna 125bv Blower and inspect it closely to determine whether it has dirt and debris on it.

You should also look out for cracks in its structure!

If the fuel filter is infiltrated by debris or is decorated with cracks, you can assume that the fuel filter is the cause of your leaf blower malfunctioning.


If the fuel filter is partially clogged, you can clean and reuse it.

However, if the situation seems dire with endless amounts of debris clinging to the fuel filter- it’s time you to replace it with a new one!

Moreover, avoid using dirty or old gas in the future and replace the fuel filter annually.

3) A Damaged or Leaking Fuel Line

Fuel lines are delicate! Their rubbery plastic base may be subject to degradation- leading to fuel leaking and excess air finding its way into the combustion chamber. This leads to less fuel and a more significant quantity of air in the combustion chamber causing the unbalance.

Using the choke forces up more fuel, balancing the mixture.

Running Diagnostics

A glance at the inside of the fuel tank will help you assess whether the fuel line is loosely dangling or if there is any fuel dripping.

If you can observe neither, you can reach into the fuel tank, detach the fuel line, and inspect it for cracks.


Firstly, avoid using high-ethanol fuel as it breaks down the fuel line much quicker.

Did the fuel lines seem detached or loosely danging? If yes, then that is the problem and, in this case, will only require you to secure the fuel line into its rightful position.

However, if you noticed fuel dripping or a crack in the fuel line was visible- you will have to replace it!

4) Worn and Old Gas

Old gas can be bad news!

After gas breaks down, it leaves varnish and deposits in its wake, which causes the leaf blower to malfunction.

Running Diagnostics

A good memory is all you need to diagnose whether you have expired gas dwindling in your blowers system.

If you have left the gas in the system for over 30 days, it is time to make some changes.


You’ll have to drain the existing gas from the blower. Next, choose the ideal gas for your Husqvarna 125b Blower.

Make sure the gasoline you choose has an octane rating of 89% or more and ethanol content of 10% or less. Now pour the chosen fuel into the fuel tank.

You may add an additive like ‘sea foam’ and ‘STA-BIL’ to provide some remedies to your blower, such as cleaning the fuel system, reducing moisture, and stabilizing the gas. However, adding a stabilizer to your gas is not mandatory.

5) A Clogged Carburetor

The fuel filter is not the only part of the Husqvarna 125bv Blower that can be invaded by debris. The carburetor can also face this dilemma!

As discussed previously, the carburetor’s central function is to maintain a balance in the fuel-air mixture. However, the carburetor may struggle to do its job if it is varnished or struck by debris.

Running Diagnostics

According to the owner’s manual of the Husqvarna 125bv Blower, the carburetor has three
adjusting screws ® for adjusting the carburetor:

  • Low-speed jet
  • High-speed jet
  • Adjustment screw for idling

If you’re accustomed to its layout, you’ll easily be able to follow the below-mentioned steps.

  1. Diligently remove all the screws holding the carburetor and take the carburetor apart.
  2. You’ll be able to tell whether varnish or dirt is clinging to its structure.
  3. If debris is on the carburetor, purchase a carburetor cleaner and remove any visible debris.
  4. Excess deposits from fuel must also be cleared up using the carburetor cleaner.

If you do not wish to clean the carburetor yourself, you can always take it to a small engine shop to get it cleaned or repaired, or you can replace the entire carburetor (they are not very expensive)

6) A Worn Out Carburetor Gasket

The carburetor gasket is positioned behind the carburetor in a leaf blower. Deterioration may overcome the carburetor gasket- causing it to allow air into the leaf blower- leading to a lean run.

A lean run in a leaf blower is when the air is in a greater quantity than the fuel- creating an unbalanced ratio. This causes the leaf blower to become dependent on the choke to run.

Running Diagnostics

After closely scrutinizing the gasket, you may be able to tell whether it is worn out or not.


Remove all the screws and linkages connecting the carburetor to the blower. After you have removed the carburetor, remove the gasket to inspect the situation.

Now install a new gasket into the blower. As a bonus, go ahead and clean the carburetor.

7) An Unadjusted Carburetor

If you have checked all other possibilities causing the leaf blower to act up, it is probably an unadjusted carburetor that is causing the issue.


Adjust the idle speed-T by using the idle adjustment T-screw. Turn the T-screw clockwise to increase the idle speed; alternatively- turn the T-screw anti-clockwise to achieve a lower idle speed.

Note- The owner’s manual recommends an idle speed of 2800-3200 rpm for the Husqvarna 125bv Blower.

Furthermore, it recommends a maximum speed of 8600rpm for blowing and a maximum speed of 7500 rpm for vacuuming.


Can There Be Problems From Operating a Husqvarna 125bv Blower on Choke?

If you force your leaf Blower to thrive on an illness, it will depreciate faster, leading to it being infested by long-term issues.

If a Husqvarna 125bv Blower continues to operate solely using a choke – your fuel consumption will increase drastically as the carburetor will be using excess fuel supplied by the choke.

This is bad not only for your pocket but also for the environment!

Furthermore, it will cause the leaf blower to continuously lose power and, at times, permanently damage the engine.

The list doesn’t end there! Having a surplus amount of fuel in the combustion chamber will deprive the walls of the engine chamber of the appropriate amount of engine oil. This will result in an unnecessary carbon build-up within the leaf blower and poor lubrication.


Most of the time, if your Husqvarna 125bv Blower is only running on a choke, the above problems are causing the malfunction. Some of these issues may also cause the blower to not start at all. We have a separate guide for the ‘no start’ diagnosis for the Husqvarna blower.

However, if you have assessed and resolved all the issues mentioned above and your blower still won’t operate without a choke- it might be time to contact a local mechanic or replace the Blower with a new one!

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