How Lawnmower Throttle Works? How To Fix a Lawnmower Throttle Cable?


A lawnmower machine has many important parts like other automobile machines. The throttle is one of the essential parts of this machine. Though it doesn’t directly control the engine speed, it plays a crucial role in determining the mower cutting speed. Understanding how lawnmower throttle works will help you determine if anything happens inside the throttle

So, how lawnmower throttle works?

With the help of throttle cables, a lawnmower throttle helps start the engine and plays a primary function to regulate the blade’s speed of the mower. Additionally, this small engine part handles the governor while running the machine.

Want to know how lawnmower throttle works in more detail? Not worry; this article will cover this topic in an in-depth discussion. Keep scrolling!

What is a Throttle?

What is a Throttle?

Before knowing how a lawnmower throttle works, let’s understand what a throttle is. We know a perfect amount of air-fuel mixture is required to run your mower engine. The speed of air that goes to the mixture is controlled by a lawnmower throttle.

The throttle does not directly determine the speed of the lawnmower. Instead, its job is to control the airflow speed, which will define the actual speed of your mower.

Do you run your lawnmower throttle partially or in a full manner? Most people don’t use the throttle at full. According to most mechanics, it is best to run them in full to get the best engine efficiency.

So, where is the throttle on a lawnmower?

Most of the old lawnmower has a manual throttle, which is attached to the intake butterfly valve of the carburetor.

But, where is the throttle on these new mowers?

Though their function is relatively different from old mowers, they are connected to the carburetor’s intake valve like old mowers. New mowers come with an automatic throttle, so you don’t need to control the fuel flow manually. So, fuel consumption and blade speed are handled automatically. 

How Does Lawnmower Throttle work?

how does lawnmower throttle work infographic

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It is important to have enough idea of how lawnmower throttle works so that you can understand how the whole system works.

The carburetor is an essential part, which helps to supply an ideal amount of air and gasoline mixture into the mower’s combustion chamber. Two butterfly valves are equipped in many carburetors, and their job is to regulate the flow of a fluid.

1. Choke Butterfly Valve

Choke Butterfly Valve

One of them is called the choke butterfly valve, and their main job is controlling or regulating how much air will enter into the mixture of gas.

This valve is fully or almost closed when the mower machine is running at a cool temperature. As a result, no air enters inside the mixture, and the combustion contains only gas.

Running the machine for several minutes increases the engine’s internal heat. So the choke valve is slowly opened. It can happen manually or automatically.

2. Another Butterfly Valve

Another Butterfly Valve

Another type of butterfly valve is located at the other end of the carburetor. Its main task is controlling the aggregate amount of fuel and air mixture, which will enter inside the combustion chamber.

A governor may be the only element that can change this. This system adjusts engine output based on torque requirements.

For instance, cutting tall and thick grass requires the mower more engaging so that it doesn’t stop at the middle of the cutting. In order to achieve this, there is basically a control loop provided by the governor.

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Additionally, there might be a separate throttle control attached to this valve. Using the lever-controlled cable, you can activate it.

However, the control mechanism of this butterfly valve is not directly related to this cable. Instead, a particular type of spring is used to provide the governor the required direction.

So, these are all important details you should know if you are wondering how lawnmower throttle works.

Why Run your Mower at Full Throttle?

Why Run your Mower at Full Throttle?

Apart from knowing how lawnmower throttle works, you should also have a basic idea of why run your mower at full throttle. Operating the whole lawnmower system for longer may depend on running the throttle at a partial capacity.

However, you will have many advantages for running throttle at full speed. Let’s learn some benefits on “Why run your mower at full throttle?”

1. Lower Pressure For The Engine

Lower Pressure For The Engine

A lawnmower engine is supposed to operate at full throttle. Running it in less capacity will low the pressure for the machine. It will cause several problems.

Battery Issue—For an electric-powered lawnmower, its battery performance will reduce, and the battery won’t hold the charge as long as it used to do.

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Besides, some batteries don’t recharge until you run the throttle at full speed because it needs to reach a specific level of RPMs.

Fuel Inefficiency—Many people believe using the throttle at low capacity will save fuel, but it does the opposite. The engine requires more quantity of fuel as it is lagging in running fully.

By optimizing the throttle capacity, you’ll also be able to reduce cylinder waste, plus it will make your engine more fuel-efficient. The pistons and other associated parts will have enhanced durability due to this.

Vibration ProblemThe lawnmower machine will have more vibration for operating with less throttle capacity. Practicing this for a long time will lead to engine failure or even damage.

For opening the throttle partially, engine parts will be vibrated at different frequencies during operation. Eventually, the engine will fail due to the stronger ones.

2. Cleaner Grass Cut

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The blades of the mower work faster when the throttle runs at full capacity. Hence, cutting thick and tall grasses quickly and efficiently is easy-going. On the other hand, you will have untidy or irregular grass cutting when using the lower throttle.

3. No Slow Operation

Unless there is enough power on your mower engine, you can’t cut thick grass smoothly. The machine, while operating at the lower throttle, may slow down and clog up.

But at full throttle, your lawnmower will operate fast, and it can take a heavy load to cut the tall, thick grass easily.

4. Less hit inside the engine

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Running the throttle at full capacity means it is fully open. Even though the engine generates heat while operating, a sufficient amount of air enters inside it via the cooling fan. So, the lawnmower works smoothly without having any issues.

So, these are the main benefits you will have if you are wondering about “Why run your mower at full throttle?”

Why a Lawn Mower Throttle May Stick in One Position?

Why a Lawn Mower Throttle May Stick in One Position?

The throttle of a lawnmower has multiple parts such as throttle arm, throttle linkage, choke lever, etc. There is a chance that they may malfunction at some point.

Fixing them soonest is what you should do to ensure smooth operation and avoid issues while cutting the lawn. Do you know why a lawn mower throttle may stick in one position? Here are few common causes that may be the culprit for it:

1. Environmental Exposure

Not all weather conditions are perfect for running a lawnmower. It should not be excessively hot, cold, or wet.

According to many experts, these types of bad weather conditions may result in poor engine performance and make the throttle stick in one position.

If any of the mower components is affected by rust, you want to treat them as early as possible for better function.

2. A Lack Of Maintenance

Like other engines, a lawnmower engine needs adequate maintenance. Over time, the throttle cover may become loose. Plus, the throttle will be incapable of holding the right amount of lubrication and moisture.

The best solution for this problem is using a spray-on lubricant. During each season, it will maintain the perfect moisture levels of the components.

3. Dirty Throttle

Dirty Throttle

Are you keeping your lawnmower idle for a long time, especially in the off-season? Dust, dirt, and grease may build up around the throttle.

Make sure you clean the throttle from the outside part properly before opening the cover. By doing so, dirt won’t get inside the throttle.

So, these are the possible causes of this question: “Why a lawn mower throttle may stick in one position?”

How To Fix a Lawnmower Throttle Cable?

How To Fix a Lawnmower Throttle Cable?

Is your lawnmower not running, or it slows down while using the throttle? You may then want to check the lawnmower throttle cable, which plays a crucial role in regulating the engine speed.

So, what is a lawnmower throttle cable? You will notice most lawnmowers’ throttle cable is located in a carburetor’s intake valve. Though the component is tiny, as soon as you pull your mower, it coordinates the working of its engine parts.

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Your lawnmower throttle cable may have various types of problems after a certain time. So, how to fix a lawnmower throttle cable? Here is the step-by-step method you want to follow to learn how to fix a lawnmower throttle cable.

Serial No Tools You Will Need
1 Screwdriver
2 Tape Measure
3 Socket Spanner
4 Pliers

Following these steps:

Step 1 — Inspecting The Throttle Lever

Inspecting The Throttle Lever

The throttle level features a handle, which is the first part you want to check out. In that case, you want to move it in various directions to see any abnormality. Make sure you move the cable before doing it.

Step 2 — Taking Off The Air Filter Casing

Taking Off The Air Filter Casing

Each air filter includes a casing. You want to take it off by using a screwdriver. This allows you to see the choke arm off the throttle, which is mainly responsible for creating a fixed amount of mixture.

Step 3 — Taking Distance Measurement

There is a gap between the throttle control lever and the throttle choke arm. The tape measure is what you will need to measure distance. For a functional throttle cable, the gap is small, ranging between 0-1 mm.

Step 4 — Loosening The Nut of Cable Adjuster

Loosening The Nut of Cable Adjuster

Is the gap more than 1 mm? If yes, you want to use a socket spanner to loosen the nut. Keeping a perfect gap between the throttle control lever and the throttle choke arm is necessary. You can pull the adjuster upward or downward to ensure proper distance.

Step 5 — Tightening The Nut of Cable Adjuster

The loosen nut essentially holds the throttle cable. Now take pliers to adjust the tension on the throttle cable after pulling it a few times.

So these are all the necessary steps you want to go through if you are wondering how to fix a lawnmower throttle cable.

How To Remove A Stuck Throttle Cable?

How To Remove A Stuck Throttle Cable?

When rust and dirt build up on the throttle cable, it may make it stuck. You can’t efficiently control the engine speed of the lawnmower if the throttle cable becomes stuck.

You need to get rid of this issue soonest so that you can operate the machine smoothly. The following steps will help you remove a stuck throttle cable:

Following these steps:

Step 1 — Detaching The Cable Connection

The throttle cable is connected with both the throttle and mower engine. You want to disconnect the connection from each end.

Before removing the cable, notice how it is connected from both ends. You can capture a photo as you need to attach the line again.

Step 2 — Linking The Funnel

A bracket supports the throttle cable. You want to loosen this bracket. Hold the end part of the throttle cable and keep a funnel at the opening of the line.

Now use the insulating tape to secure the position of the funnel, which you have placed on the cable opening. This will close the mouth.

Step 3 — Using Penetrating Fluid

Reach the other side of the throttle cable to keep a pot under it. So, when you pour the penetrating fluid through the funnel, it will accumulate on the pot.

Keep pouring a decent amount of liquid to remove the rust and dirt from the cable. Make sure no liquid is stored inside the throttle cable. Let it drain properly.

Step 4 — Adjusting Throttle Internal Cable

Adjusting Throttle Internal Cable

Has the liquid drained? Then, you want to put your hands on the internal throttle cable using a plier. Ensure a free movement of the line by moving above and below direction.

Step 5 — Using Dielectric Grease

Lastly, you want to apply Dielectric Grease by spraying it on the cable surface. After doing all these steps, the throttle is supposed to be free from struck.

Then, you should remove the funnel from the cable mouth and keep it back in its original position.


  • It is best to detach the connection of the spark plug before you repair this engine part.
  • Make sure you wear all the essential protective gear for maximum safety.

That’s all the steps you want to follow to learn how to fix a lawnmower throttle cable if it gets stuck.

How Does Throttle Cable Break?

How Does Throttle Cable Break?

You can’t run a lawnmower unless there is power. If the throttle cable breaks, the lawnmower engine will not be powered.

How does throttle cable break?

When you use the lawnmower for several years, the cable gets extended, causing breaking issues. If this happens, you will struggle to push the throttle cable. It is an early sign your cable needs a replacement.

You can either purchase a new throttle cable or follow a DIY method to make it. If you are expert enough to fix the issue by yourself, you will save some money. It will cost you only $2-$3 to buy the essential things.

However, if you don’t want to take the mess of fixing it, you can order it from Amazon. For a ready-made throttle cable, you will have to spend approximately $15-16. Since it will take several days, you have to wait for the product to be delivered to replace the cable.

Hopefully, you have learned how does throttle cable breaks and which type of option you have to deal with it.

Symptoms Of A Bad Or Failing Throttle Cable

How do you know whether your throttle cable has become bad or not? You can understand by seeing some symptoms. Here are they:

1. Slow Acceleration Response

The throttle is supposed to respond immediately when you pull it. If you notice it responds slowly, you may pull it more times unconsciously. In that case, you want to check out the condition of the throttle cable.

2. Dirty Or Frayed Cable

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If there is any dirt or grease build-up on the throttle cable for a long time, it may stick in particular positions, making it broken or damaged after a certain time.

3. Fuel Inefficiency

If your lawnmower is consuming more fuel more than usual, you want to check out the throttle cable to see any issue appears on it.

Final Thought

All components of a lawnmower are closely related to each other. Unless you ensure each of them doesn’t have any issue, you can’t run your lawnmower properly. Like other parts, the throttle is another essential part. Knowing how the lawnmower throttle works helps you to understand its function properly. If anything happens on that particular part, you can figure it out easily.

Last update on 2022-01-17 / Affiliate links / Images from Amazon Product Advertising API