Fixing Cub Cadet’s Choke-On Only Mower!

You are able to keep your mower going, but you will need to make use of the choke if you want to do so. If you are using a lawn mower with the choke engaged, it is an indication that you have an underlying problem that has to be repaired before it has the potential to become a significant issue.

It’s possible that the choke on a Cub Cadet lawn mower is the only way to get it to operate if the engine is receiving either too much air or not enough gasoline.

It’s possible that this is the result of a filthy carburetor, stale gas, a clogged fuel filter, a damaged fuel pump, a faulty gas cap, a blocked or punctured fuel line, or a broken carburetor gasket.

For a complete rundown of all safety measures, see the operator’s handbook that came packaged with your Cub Cadet. Before beginning any repairs, it is necessary to take precautions such as removing the ignition key and the spark plug boot.

There are a few reasons why your Cub Cadet lawn mower won’t start until you turn the choke on:

  • Due to a lack of gasoline
    • Used fuel
    • An unclean carburetor
    • Clogged fuel line
    • Defective fuel pump
    • Blocked fuel filter
    • Defective fuel cap
  • A surplus of air
    • Defective carburetor gasket
    • A hole was found in the fuel line.

outdoorstip Cub Cadet Mower

There are 6 main reasons why a Cub Cadet lawn mower will not run without the choke engaged.

Using Outdated Fuel in a Cub Cadet Mower

As soon as thirty days have passed after the first purchase, gas might turn stale and begin to deteriorate. The deleterious effects that ethanol has on the Cub Cadet tiny engine are caused by the fact that most gasoline contains it.

The gasoline system might pick up moisture when ethanol is present. This combination of water and ethanol not only leaves behind varnish and deposits that limit the amount of fuel that can be used, but it also causes corrosion.

Because of this, it is essential to choose the appropriate fuel and use it as rapidly as possible.

Mowers manufactured by Cub Cadet must be fueled with unleaded gasoline that has an octane value of at least 87 and no more than 10% ethanol. Never run your vehicle on gas that has more than 10% ethanol in it.

Here you may learn more about how to choose the fuel that is best for your Cub Cadet.

SOLUTION: Remove any stale gas from the tank before driving. In order to assist clean the fuel system and prevent moisture, add some new gas that has a fuel additive already mixed into it.

Sea Foam Motor Therapy is a product that I like using. You may learn more about the positive effects that Sea Foam has on your fuel system and engine by reading more about them here.

A Cub Cadet Lawn Mower May Have a Puncture or Blockage in the Fuel Line.

If the gasoline line becomes punctured, it might allow air to be sucked into the line, which would then cause the engine to receive an excessive amount of air. Alternatively, there is the possibility that a clog may form in the line, which would reduce the quantity of gasoline that is supplied to the engine.

If one of these problems is present, the lawn mower may only start when the choke is engaged. This is because the choke is used to regulate the amount of air that enters the engine, which in turn helps maintain the correct fuel-to-air ratio that is necessary for combustion.

SOLUTION: Examine the gasoline lines carefully. Follow the line that is emerging from the gasoline line, and then follow that line all the way up to the carburetor. Examine the fuel system for any holes, punctures, or fractures that could allow air to enter.

Next, inspect the fuel line for any obstructions that might cause fuel flow restrictions. To begin, use the fuel shut-off valve to stop the flow of fuel via the fuel system. The next step is to cut off the end of a segment of the gasoline line and put it in a container specifically designed for fuel collection.

After turning the fuel flow back on, check to ensure that a sufficient amount of fuel is entering the container from the fuel line. Turn off the gasoline supply and remove the fuel line from your Cub Cadet if you are not receiving a satisfactory flow from the fuel tank.

In order to break up the blockage, spray some carburetor cleaning into the pipe. After this, you should use compressed air to remove the obstruction. That is vital to repeat.

If you simply are unable to get the fuel line clean and the clog cleared, or if you discover a puncture in the fuel line, you will need to replace the damaged portion with a new length of fuel line that has the same diameter.

A Cub Cadet Lawn Mower That Has A Clogged Fuel Filter

The fuel filter is a tiny component that is installed in the gasoline system between the fuel lines. Its purpose is to prevent dirt and other pollutants from entering the fuel system and causing the engine to get worn out.

This is a component that has to be updated on a yearly basis in order to maintain it in excellent shape. As it gets clogged, it may limit the quantity of fuel that is able to travel through the filter, which may be an inconvenience.

Because of the decreased quantity of fuel, the choke may need to be employed in order to get the proper mixture of fuel and air necessary for combustion.

SOLUTION: After removing the fuel filter, install a new inline fuel filter in the area that was previously occupied by the fuel filter. An arrow should be located on one of the housing sides of the filter, and it should point in the desired direction.

In order to properly install the filter, it is required to position it in such a manner that the arrow points in the same direction as the flow of gasoline.

A Cub Cadet Lawnmower with a Defective Fuel Pump

In the event that the carburetor is positioned higher than the gasoline tank, your Cub Cadet will need the usage of a fuel pump. The majority of mowers make use of a vacuum pump, which transfers gasoline from the fuel tank to the carburetor by using the vacuum created by the engine.

In order to test the fuel pump, you will first need to ensure that fuel is being supplied to the pump’s input port. The next step is to detach the fuel line from the carburetor and put it in a container large enough to collect gasoline while you test the flow of fuel flowing out of the line.

SOLUTION: In the event that you discover any fractures or gasoline leaks, as well as if the fuel flow is insufficient, you should switch out the fuel pump with a new one.

A Cub Cadet Lawnmower with a Defective Carburetor Gasket

It’s possible that the gasket that protects the area behind the Cub Cadet carburetor may wear out over time. When this occurs, the seal is no longer effective, which allows extra air to enter the system and causes the engine to operate in a leaner state.

When an engine is said to be running lean, there is a greater concentration of air and a lower fuel concentration than is needed by the engine. In order to compensate for the additional air that is being drawn into the engine due to a faulty carburetor gasket, the choke will need to be turned on.

SOLUTION: It is necessary to first remove the linkages and bolts that are fastening the carburetor in order to have access to it. Remove the gasket and the carburetor off of the engine and set them aside.

After installing the brand-new gasket in place of the worn-out one, reassemble the carburetor together with the bolt and the linkages. After the carburetor is removed from the mower, you will also have a great opportunity to determine whether or not it needs to be cleaned. This may be done while the mower is still in your possession.

A Cub Cadet Lawn Mower with an Unclean Carburetor

A carburetor is required in order to control the quantity of gas that is combined with the air during the combustion process. When it becomes filthy, which is probably because of old gas, the fuel pathways and internal components may get blocked and stop working properly. This is likely to happen.

In order for the engine to get the appropriate quantity of gasoline and function properly, the carburetor will need to be either cleaned or changed.


You should be able to take apart and clean the Cub Cadet carburetor on your own if you have a fundamental grasp of mechanics and don’t mind handling sensitive components. All you need to do is follow the steps in these instructions, and they will walk you through the process.

If, after cleaning the carburetor, you put it back together and it still does not function correctly, you will need to either fix it or replace it.

You might take your mower to a dealer that specializes in tiny engines if you don’t feel like cleaning it yourself. They will be able to do it for you.

A Cub Cadet Mower with a Defective Gas Cap

In order for the fuel tank of a Cub Cadet mower to function properly, it has to have a vent that lets air into the tank even while gasoline is being used up. In the event that it is unable to vent, the fuel tank will experience the formation of a vacuum.

By doing this, you will prevent petrol from leaking out of the tank and reaching the carburetor.

The Cub Cadet’s gas cap serves as the opening for the fuel tank’s venting system. It is necessary to replace the cap if it becomes cracked or blocked.


One method for determining whether or not the gas cap is faulty and whether or not it needs to be changed is to loosen the gas cap so that air may enter the tank. This can help you decide whether or not the gas cap needs to be replaced. If you are able to remove the choke from the engine and it continues to operate normally, the issue may be with the cap.

Make an attempt to recreate the problem in order to offer more evidence indicating that the cap is defective. While the engine is running, the cap has to have additional tension applied to it.

If the engine begins to run more slowly than it normally does, and you have to engage the choke in order to keep it running, but you are able to remove the choke when the cap is loosened, the problem is most likely caused by the cap. Replace a defective cap.

Are You Still Experiencing Issues with Your Cub Cadet Lawnmower?

Check out my guide that details the most common Cub Cadet issues and how to solve them if you are experiencing difficulties with your Cub Cadet that are not addressed in these recommendations or if you are having problems with your Cub Cadet that are not addressed in these suggestions. Issues that crop up often with Cub Cadet products.

In this part, you will learn the causes behind Cub Cadet difficulties such as the mower not starting, a poor cut, a vibration, or a smoke issue. You will also find how to solve these problems. I not only provide answers, but also connections to further content that is deeper in nature.