Fixing Lawn Mower Automatic Choke Problems Easily!

Yes, we know how irritating it feels when your lawnmower doesn’t start at all or start initially then stops running.

In fact, this is not the end. There are other lawnmower automatic choke problems that can cause your headache.

However, we are here to divide your burden. Here, in this article, we’ll talk about the most common issues, why the issues show up, and how you can solve them.

Also, there’s an FAQ section in the end that will answer the most common questions related to the topic. So, you will leave knowing every necessary information concerning the choke problems.

Let’s jump in!

The Fundamentals of A Lawn Mower Automatic Choke

Although the question- ‘how does a lawnmower automatic choke work?’ is more like the tip of the iceberg here, this will help you to deal with the problems more easily.

The automatic choke is a valve of the carburetor that maintains the proper ratio of the air & fuel mixture when the engine cranks. It adjusts the temperature change when the engine warms up and allows the ideal amount of air to get in. 

So, when the choke prevents unnecessary airflow to get in, it enriches the air & fuel mixture at the same time. And, this process is crucial to start the engine.

Now, you need to know the answer to ‘where is the choke on a riding lawnmower?’ to troubleshoot the relevant problems.

Well, the choke is next to the seat on the left side. Some mowers come with a manual choke which you’ll notice easily. But others have the choke and throttle lever combined. However, you’ll clearly notice it in either way because there’s a choke symbol.

Now, we can head over to the problem-solving option.

Also Read: 3 Most Common Lawn Mower Ignition Switch Problems

3 Most Common Lawn Mower Automatic Choke Problems

These three problems are fairly common that most of the users face. Let’s discuss the issues, the reasons behind them, and how you can deal with them.

1. Lawn Mower Won’t Start

You may have tried for a while but the mower did not start on its own. Now, your question is- why my lawnmower won’t start?’, right?

The problem is with the automatic choke of your mower. The choke butterfly is not closing properly even if you try to get it to shut, it’ll open up again. Why this does happen is because the whole arm that holds the auto choke mechanism is somehow pushed too far out toward the carburetor.

If the further question arises that how it’s pushed too far, well, it’s maybe from vibration or somebody hits something and moves it somewhere along.

So, how can you possibly fix it? Some people replace the spark plug right away to solve this. But hey, this will not work here.

These steps below will get to the root cause of the problem and let you have a permanent cure.

Step 1: Remove the Air Filter Assembly

The first thing you’ll do is to make sure that the engine is cold.

Then, you’ll find two bolts that hold the air filter assembly on the carburetor, remove them. You will want to use an impact gun with an 8mm socket to do the job. If you do it right, the whole air filter assembly should come right off.

Step 2: Follow the Throttle Linkage Cable Towards the Carburetor

Here, you are going to follow the throttle linkage cable towards the carburetor where the choke mechanism exactly is. As we said, the choke mechanism is pushed too far out towards the carburetor, you’ll see it yourself.

Step 3: Use a Pair of Pliers to Pull Things Back

To make the solution, use your pliers and pull the things back. While doing so, start in small increments like less than a quarter-inch. This is how you should push the choke mechanism toward the opposite, away from the carburetor.

You can see that the choke butterfly is nice and closed. To test if things are perfect, push the choke open and see if it closes up again. 

Now, start the mower, and voila! It will start on its own if you follow the instructions right.

2. The Automatic Choke System Gets Flooded

Is your mower locked up and it stopped running even if it was successfully started?

If yes, then the choke system is flooding. Sounds complicated?

Well, let me explain how it happens.

The engine started perfectly, you left it at full choke for around a couple of seconds and too much fuel entered into the combustion center. So, this is what ‘the engine’s been flooded’ means.

For this issue, it will take quite a long time for the fuel to drain out of the chamber and to the exact point where your mower is fine to start again. If things are worse, maybe you’ll have to open up the engine in order to drain the fuel and get things back to normal.

So, how can you possibly solve this?

While dealing with the problem, you may never start the locked engine on the very first pull of the cord. So, pull the cord until you notice that the engine is on the right track of starting rather than constantly pulling the cord on full choke.

When you can feel that ‘yes! The next pull is gonna start it!’, carefully place the lever to half-choke. It will let some air enter as well as reduce the chances of your engine is flooded.

3. The Automatic Choke is Stuck

We’ve talked about a situation when the choke is loose and it doesn’t close properly.

But in this case, the choke may not open and close, it sticks and doesn’t move. This reason also leads the engine to a flooding situation even when you follow the correct steps to start it. A stuck choke is never good because it doesn’t let the engine start perfectly.

The first thing you should know is the reasons why the automatic choke gets stuck.

There are two main reasons for the consequence- choke rod rusting and choke piece failure. It’s natural that the choke rod will rust over time but when it’s too rusted to salvage, the choke piece failure will occur.

If you lubricate the choke shaft to maintain it properly, rust build-up may not show up. Sometimes, improper storage is what causes the choke rod to rust. When you constantly fail to put the mower away in a sheltered area during bad weather conditions days, rust can happen.

And, over time, this simple rust can cause the choke to be worn and damaged, and finally, the choke piece failure will make you upset. 

It’s important to take things into consideration when the choke is sticking only slightly. Otherwise, the dirt will keep building up until the choke gets totally stuck.

So, you must check and lubricate the choke shaft and the choke linkage regularly. It’s pretty easy to spray carburetor cleaner to the shaft for loosening the grit. It will let the choke return working correctly.

Also, store the mower in a dry and cool area to prevent the unwanted rusting process.

Frequently Asked Questions

Should the choke be open or closed when starting?

The engine should be closed while starting a cold engine. It will allow more or less air into the engine of your mower and maintain a perfect air-fuel ratio.

The mower only runs with the choke on, is it bad?

Yes, chances are there’s a problem with the carburetor. Then, you should clean the carburetor. If the problem isn’t solved, replace the carburetor.

What if you leave the choke on?

If you leave the choke on a long time, it may lead the engine to wear, waste fuel, or other unwanted situations. It’s also bad for the environment. 


See how far you’ve managed to be in this post! Hopefully, you’ve got your desired information regarding lawn mower automatic choke problems.

The automatic choke is a tiny piece of equipment, it’s not so hard to understand the part and deal with the relevant problems. If you keep the carburetor clean, lubricate the choke shaft regularly, you can seal the chances of facing any issue with the automatic choke. 

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