Any lawn mower who has ever had trouble starting a mower will understand the significance of choke. A bulky engine can bring so much frustration. The choke plays an important role during the moment between starting the mower machine and pushing forward to cut the blades.

Mower chokes vary; while some are automatic, others are manual. Nevertheless, all mower engines have a mechanism to control the ratio of air to gasoline in the carburetor. 

What is choke?

A choke or a choke valve is a manual valve that moderates the amount of air flowing into the fuel-air mixture. Primarily, the choke is used to reduce or restrict the airflow into the carburetor when you are trying to start your machine.

Restricting the air causes more fuel to be pushed inside the combustion chambers. This helps the fuel to evaporate well in most small engines that are being started cold. Generally, for fuel-powered lawnmowers, the choke plays the following roles:

  • Restricting airflow into the carburetor, which in turn leads to low internal pressure, thus more fuel is pushed into the mower’s combustion chamber.
  • Helps supply a richer fuel-air mixture to the mower engine, and in return, allows combustion. This ensures that the cold mower runs efficiently until it warms up enough for the engine to run on an open choke without going off.
  • The choke creates a higher partial vacuum which ensures more fuel is pushed into the combustion chamber.
  • It’s also true to say that choke increases the effectiveness and the general lifespan of a riding lawn mower.

How to Start Lawn Mower with Choke?

How to Start Lawn Mower with Choke?

To start a lawn mower with a choke, you first have to turn the ignition switch. This switch is mostly found on the dashboard. In some mowers, however, you can find the switch next to the seat. After turning the switch on, move the air valve up and down by using the choke lever.

Turn the choke lever back to the open position to begin your engine. After the engine starts, you should close the choke. You can now return to the throttle.

If the choke is off while starting the engine, you can try turning it on. Although this will help your cold mower’s engine start up, you should be careful when doing it since extra fuel will be added to the carburetor thus flooding it. Keep in mind that the choke helps you control the amount of fuel that your mower needs.

Notably, there are two system types that manufacturers use to achieve hassle-free cold starts. First, we have the choke plate type that you can control with a lever. Secondly, there is a primer bulb that is simplified and much easy to use compared to the plate.

Whether you opt for the choke plate or the primer bulb, both systems work under the same mechanisms: creating a fuel-rich condition by jetting more fuel into the mower’s engine.

All that said, here is a simplified step-by-step guide on how to start a lawnmower with a choke:

  • Pick a Suitable Position

When you want to use the choke on a lawn mower, the first step is to pick a suitable position. You don’t want to spoil your tall grass to catch the sharp mower blades – At least not before you have the correct height setting on the mower.

For the primer bulb type system, you’ll need to press it thrice but for the throttle lever type; you’ll need to move the lever to full choke.

  • Bail Lever

The dead man’s lever or the bail lever is a bar located at the top of the handlebars and is marked with a “stop” symbol. This is a safety feature that is used to stop the engine and the blades from spinning within three seconds.

  • Yank The Pull Cord

This will help the mower engine produce a strong spark and ignite the fuel. However, some mowers may require more than one pull to start. If your mower does not start after the first pull, you should leave it for a couple of minutes to one hour, and then try pulling the cord again.

If the engine requires more than three pulls to start, the fuel may flood the engine, so you should leave it for approximately 30 minutes. After this time gap, try again, but this time with the choke-off.

  • After The Engine Has Warmed Up, Move the Throttle Lever to “Fast/Run”

Note that running your mower engine when the choke is on may potentially damage your engine. First, the mower will give off black smoke and of course, run poorly. 

Starting Tip: To start small engines with a priming bulb system using a choke, hit the priming bulb at least 5 and at most 10 times with the choke on full. Proceed by pulling the cord or turning the ignition switch/ key until the mower engine sputters.

Next, reduce the choke from full to half and start the engine. After a few minutes of warming, turn off the choke. With the choke-off, the engine can now run normally and allow for optimal air intake.

What is the Choke Position on Lawn Mower?

Well, on a lawn mower, the choke is mostly located next to the seat, on the left side. The manual choke is easy to notice. However, some mowers have the choke and throttle lever combined.

In either case, it is easy to identify the choke since there’s a choke symbol.

How Do You Start Choke Engine?

A choke is designed to help reduce the stress of starting cold engines. As such, a choke is considered part of the engine’s transmission system. So, how do you start a choked engine? To answer this popular question, let’s start with the basics.

Principally, gasoline or petrol requires some heat to vaporize and allow the engine to start up. Now, if the outside temperatures are colder or below freezing, the rate of gasoline vaporization will decrease – you’ll have a hard time starting your engine.

For this reason, most gasoline engines require an external source of heat to start and the Choke is best fitted for this purpose, especially if you’ve been storing your equipment for a long time. So, here is a step-by-step guide on how to start a choked engine:

  • Step 1:

Set the choke on full (closed)

  • Step 2:

Start the engine following all the guidelines as detailed in the manufacturer’s manual. After this, pull the ignition cord or press the starter.

  • Step 3:

Adjust the lever to decrease the amount of choke slowly over a couple of minutes until the engine warms up enough.

  • Step 4:

Once the engine is running smoothly, open the choke. Note that you should not leave the choke on once the engine starts operating normally. If the choke is left on, there will be excessive fuel consumption that may flood the engine causing your equipment to shut down.

When Should I Use Choke on my Lawn Mower?

To start a cold lawn mower engine successfully, you’ll need to operate the choke. The mower will warm up after idling the engine for just a few minutes or even seconds – depending on the type and brand of equipment you are using. As such, choke on the lawn mower is used in the following cases:

  • When the mower has been in storage for a long time
  • When the external temperatures are freezing

How Do You Tell if the Choke is On or Off?

Most lawn owners have a difficult time identifying whether the Choke switch is on or off. For choke with a bulb, a light turning on makes it easier to tell if the switch is on or off but what about the case without a bulb? What would indicate when the choke is on or off?

When the choke is On, the lever points to a horizontal or an angled line. Besides, this can also be designated by inscriptions like “Start,” ‘Choke,” or “Full Choke.” On the other hand, if the choke is Off, the lever points to a vertical line or the inscription “Run.”

What Happens if the Choke is Left On?

This is a broad question that could go three ways:

  1. What happens if the choke is left on during starting?
  2. What happens if the choke is left on after turning on the mower?
  3. What happens choke is left on after using the lawn mower?

The definite answer to any of these questions is ‘No.” When starting the lawn equipment, the choke is only used to help gasoline-powered mowers with cold engines. That is; equipment that has been stored for too long or when the external temperatures are too low.

After the engine warms enough, the choke should be closed – Leaving the choke on when running small engine lawn tools can cause problems. Moreover, the choke should be turned off when you want to winterize or summarize your lawn equipment.

  • Leaving Choke On During Starting

When the choke is on, more fuel is jetted into the combustion chamber. Simply put, the choke controls the air-fuel ratio thus allowing the carburetor to function adequately. As such, it is important to turn on the choke before using equipment, especially when the temperatures are freezing or at the end of a storing session for your lawn equipment. More on this is covered in the article.

  • Leaving Choke On During Operation

Once the cold engine has warmed up for a few seconds, the choke doesn’t need to be on. Operating the mower with the choke on for long periods leads to sluggish performance and may shorten the life of your lawn care equipment.

Besides, a mower on full choke produces black smoke, uses more fuel over less time, and causes the engine to overheat. All these may happen due to the following:

1) Flooding:

Leaving the choke on after the engine has started running smoothly causes excess fuel to enter the combustion chamber. What’s worse, flooding may cause the engine to lock up and stall. You surely don’t want to waste your precious time draining the fuel out of the chamber. 

2) Clogged Carburetor

Does your lawn mower start well with a choke but die off immediately after the choke is turned off? This may be caused by flooding. In other words, fuel lines in the carburetor may partially be blocked by debris. This mostly happens due to faultiness with the starting and closing of the choke. The best way to solve this is to clean the carburetor, or better still, replace it. 

  • Leaving Choke On When Storing

When you turn off the lawn mower, also ensure that you turn off the choke as well. Besides, you should ensure the choke is turned off during storage. 

How to Start a Lawn Mower in One Pull?

To start your lawn mower in one pull:

  • Stand directly behind the mower
  • Pull the chord straight towards you with high energy, this will do!

However, for your mower to start with one pull, it has to have enough high-quality gasoline, clean air filters, and clean or stabilized oil. 

Lawn Mower Automatic Choke Problems

If you’ve tried starting your mower but it simply won’t start, here are some common automatic choke problems that it may be facing, they include:

  • Lawn Mower won’t Start

The choke butterfly may not be closing properly because the whole arm system that holds the auto choke mechanism is displaced. To fix this, you’ll need to remove the air filters, follow the cable that links the throttle to the carburetor, and use pliers to pull things back in place.

  • Flooding of the Automatic choke System

Depending on the amount of excess fuel in the combustion chamber, you might need to open up the engine and drain the excess fuel. To avoid flooding, ensure that you do not leave your equipment on full choke even after the engine has started running normally.

  • The Automatic Choke is Stuck

In this case, the choke sticks and doesn’t move – whether you want to open or close. This mostly results from rust. As such, you should regularly lubricate the choke shaft.

How Do You Start a Stubborn Lawn Mower?

There is no sound as disheartening as that of a lawn mower that runs over but doesn’t start – you pull the cord several times but the engine only sputters and dies off. The first thing that comes to our mind is to replace some parts or send the mower for repair.

However, before you invest in the costly replacement parts or drag your mower for repairs, there are a few steps that you can take to get your mower up and running in no time:

  1. Use Choke to start your mower
  2. Check the spark plug to ensure that it is not loosened, disconnected, or coated in carbon residue or water
  3. Remove all blocking debris from your mower deck
  4. Change the clogged lawn mower carburetor filter
  5. Clean and refill the mower’s fuel tank
  6. Use stabilized fuel


Although it might seem a little tricky, a lawn mower choke is very efficient and straightforward to operate once you’ve given it a try. Nevertheless, you should follow all the guidelines as outlined in this article – you don’t want to flood or clog your mower’s fuel system.

Victoria Peterson

I am a passionate gardener who wants to help you create and maintain your dream yard. I know that it can be daunting to take on a project like this, but I am here to help. I have been gardening for years and have learned a lot along the way. I want to share my knowledge with you and help you create the perfect yard for your home.

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