When the choke is engaged, the Toro lawn mower starts to operate (FIX IT NOW)

You were able to start your mower, but this time when you set the throttle to the open position to keep the engine going until it heats, it sputters and dies. You will need to maintain the choke engaged in order to keep the engine going.

When troubleshooting a Toro mower that will only run with the choke engaged, search for objects or locations that enable the engine to get an excessive amount of air or an insufficient amount of fuel.

This might be the result of a filthy carburetor, stale gas, a clogged fuel filter, a malfunctioning fuel pump, a defective gas cap, a blocked or pierced fuel line, or a damaged carburetor gasket.

Please refer to the operator’s handbook that came with your Toro for any and all safety concerns. Before beginning any repairs, it is necessary to take precautions such as removing the ignition key and the spark plug boot.

The following are some of the reasons why your Toro lawn mower will only operate with the choke engaged:

  • Lack of gasoline
    • Old gas
    • An unclean carburetor
    • Clogged fuel line
    • Bad fuel pump
    • Plugged fuel filter
    • Bad fuel cap
  • A surplus of air
    • Bad carburetor gasket
    • A hole was found in the fuel line.

toro mower

7 Explanations for Why a Toro Mower Won’t Start Unless the Choke Is Engaged

1. Utilizing Outdated Gasoline in a Lawnmower

There is a short shelf life for gasoline. As soon as a month or two after you acquire it, it may already have started to show signs of wear and tear. The repercussions of using gas that is too old will cause the fuel system to jam up and will cause components to corrode.

Ethanol, an alternative kind of fuel, is often blended with most gasoline supplied in today’s market. Although this product is healthier for the environment, it should not be used in engines that are very tiny, such as the one that is used on a Toro.

Ethanol causes the gasoline to take in moisture from the surrounding air. The ethanol and the water will eventually separate from the gasoline and make their way to the storage tank’s bottom.

When it evaporates, it leaves behind gummy deposits, and the water that is left behind is corrosive and may destroy the components of the fuel.

It’s possible for the engine to be deprived of a sufficient quantity of gasoline if the fuel system’s components aren’t functioning properly or if blockages form in the fuel system. It’s possible that in order to keep the engine going, you’ll need to adjust the gas-to-air ratio using the choke. This is because combustion requires a certain ratio of gas to air.

Toro mowers need unleaded fuel with a minimum 87-octane rating and a maximum 10% ethanol content. Never run your vehicle on gas that has more than 10% ethanol in it.

Find out more about how to choose the proper fuel for your Toro mower by clicking here.

SOLUTION : Remove any stale gas from the tank before driving. To assist in cleaning and reducing the amount of moisture in the fuel system, add new gas to the tank along with a fuel additive such as Sea Foam Motor Treatment or STA-BIL.

It will also maintain the gas’s stability, allowing it to remain intact for a longer period of time before it begins to degrade. Read this post to learn the reasons why I opt to put Sea Foam in every single one of my little engines.

2. A Toro Lawnmower with a Soiled Carburetor

The carburetor is the part that regulates the amount of gas that is mixed with air to form combustion. This is the place a little gas is stored after it leaves the fuel tank.

Old gas is often the reason a Toro carburetor fails. It coats the inside of the carburetor clogging fuel passageways and causing internal carburetor parts to stick.

Because of the fuel limitation, it’s possible that you’ll need to adjust the mixture of gasoline and air in the engine using the choke in order to keep the vehicle operating.

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.


If you are somewhat mechanically inclined and don’t mind dealing with tiny components, you should be able to remove and clean the Toro mower carburetor on your own by following the directions in this article.

After following these procedures to clean the carburetor, if it still does not function properly, you will likely need to either rebuild it or replace it. If you don’t feel like doing the task on your own, you may have a technician that specializes in working on tiny engines clean or repair the carburetor for you.

3. A Toro Lawnmower has either a puncture or a clog in its fuel line.

If the gasoline line is punctured, air may be sucked into the line, which would then cause the engine to receive an excessive amount of air. Or, 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.

Either of these problems might be the reason of your lawn mower’s inability to start until the choke is engaged. The choke is used to regulate the amount of air that enters the engine, which in turn helps maintain the correct air-to-fuel 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, examine the gasoline line for any obstructions that could be preventing fuel from flowing freely. First, 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 disconnect the fuel line from your mower if you are not receiving a sufficient amount of flow.

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. It 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 that piece of the fuel line with a new section of the fuel line that has the same diameter.

4. The fuel filter on a Toro mower was clogged with debris

Another potential source of gasoline limitation is the fuel filter, which is often located in the space between the fuel lines of the vehicle. It is necessary to have this filter in order to prevent debris from getting into the fuel system and wearing out the engine.

It is possible for the filter on your Toro to get clogged if it is not frequently updated as part of your maintenance routine to ensure that it remains in excellent shape. Because of this, an adequate flow of gasoline will not be able to reach the carburetor.

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

SOLUTION: After removing a filter that has become clogged with debris, install a new inline fuel filter between the fuel lines.

On one of the housing sides of the filter, you should locate an arrow. It is necessary to install the filter in such a way that the arrow points in the same direction as the gasoline flow.

5. A Toro Lawnmower with a Defective Fuel Pump

In order to transfer gasoline uphill to the carburetor on your Toro mower, you will need to utilize a fuel pump. The majority of mowers make use of a suction pump. The gasoline is moved from the fuel tank to the carburetor by a pump of this sort, which makes advantage of 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.

6. A Toro Lawnmower with a Defective Carburetor Gasket

Behind the carburetor, you will locate a gasket that is attached to the component. This gasket is subject to wear and tear, which may cause it to lose its ability to effectively seal. This may result in air being sucked into the system, which makes the engine run more richly than it should.

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. Because of the faulty gasket, you will need to make use of the choke in order to compensate for the additional air that is being drawn into the engine.

Carry out an inspection of the carburetor and check to see that all of the bolts are secured firmly and that the gasket is in excellent shape.

SOLUTION: If you notice that the gasket is no longer effective at sealing, you will need to obtain access to the carburetor and gently remove the linkages and bolts that are attaching it. Take the carburetor and the gasket off of the engine.

Replace the old gasket with a brand-new one, then rejoin the carburetor, the bolt, and the linkages. While you have the carburetor removed from the mower, this is also an excellent chance to identify whether or not it needs to be cleaned.

7. A Toro Mower with a Defective Gas Cap

It is necessary for the gasoline tank to have a vent that enables air to enter the tank. When the vent is blocked and air is prevented from entering the fuel tank, a vacuum will develop within the tank. Because of the vacuum, the gasoline won’t be able to reach the carburetor.

On a Toro lawn mower, the gas cap also serves as the opening to the fuel tank vent. Checking to see whether there is a vacuum buildup may be done using a pressure gauge, or you can do it by following these steps:

  • Turn the gas cap counterclockwise to let air into the tank.
  • Make sure the choke is turned all the way off.
  • If the engine continues to run without the choke being in the on position, the fault may be with the cap.
  • Make an effort to reproduce the issue so that you can be sure the cap is faulty.
  • Pull the plug and make sure the engine is running without the choke while you tighten the cap
  • If you notice that the engine starts to splutter after a time and won’t run smoothly unless you unscrew the cap, you probably have a faulty cap.

SOLUTION: Replace a faulty gas cap.

Continue to Experience Difficulties with Your Toro Lawn Mower?

Owning a lawn mower that never gives you any trouble would be fantastic, but unfortunately, this is almost never the case. The longer you keep your mower, regardless of what brand it is, the more likely it is that you may have issues with it.

I have included a list of frequent problems, along with their potential causes and potential remedies, in order to assist you in troubleshooting any issues you may be having with your Toro mower. For further information, have a look at Common Toro Lawn Mower Problems and Solutions.