What Causes Lawn Mower Not To Start? Find Out Here

Written By James
Updated July 26, 2021 by James

What Causes Lawn Mower Not To Start? Find Out Here

As teens, many of us found ourselves in the midst of a hot summer day and while thinking of something to do on this sunny day, we decided to mow our lawns. But, later on, we realized that the lawn mower is simply not working and we are not able to start it.

Why does that happen?

Most of the time, the lawn mowers were used for the last time for the last season and they are stored away in the garage for the winter months.

During the winter months, the lawn mower is poorly maintained and the fuel in it becomes contaminated and the fuel line becomes clogged. This is what usually results in the lawn mower not starting properly.

Top 5 common reasons your lawn mower won't start after a long winter:

The spring season means more than just cleaning up the winter debris—it also means it's time to start the lawn mower.

But if you have an older model, it might not start on the first try.

Before you panic, you can try these five (5) common reasons your lawn mower won't start, and you can get back to the task of mowing.

1. Always check the spark plug first

When your lawn mower won't start, it's easy to assume the carburetor is to blame, or the gas tank is empty, or the spark plug is bad. (When you're dealing with a machine, simple explanations are often the correct ones, right?)

But before you throw in the towel, try checking the spark plug first. Why? Because a bad spark plug is actually a pretty common reason why lawn mowers won't start.

Before you even think about pull starting your lawn mower, make sure the spark plug is connected. When the mower won't start, the most common reason is simply a bad or loose spark plug.

Other issues can include a dead battery or a faulty ignition switch, but the spark plug is the first thing to check. Before you can check the spark plug, however, you will need to remove the air filter cover, air filter and spark plug wire.

2. Check for fuel

The fuel in your lawn mower is really important as it runs the engine and it can get gummed up if there is too much water in your fuel. A clean fuel tank and fuel lines are essential for your lawn mower to run correctly.

You can prevent problems by doing the following: If the fuel is a little bit old and stale then it is better to put fresh fuel into the gas tank.

Failing to start your lawn mower is frustrating. While lawn mower fuel is a common source of engine problems, there are many more potential problems that can cause your lawn mower to fail to start.

After the engine has been off for more than 10 minutes, the fuel line will be empty. Some fuel will remain inside the carburetor and tank but not enough to start the engine.

The solution is to tip the lawnmower on its side and turn the fuel line on the bottom of the tank to start the flow of fuel into the carburetor and then into the engine.

3. Clog in the carburetor

When your lawn mower engine fails to start, you can be sure there is a clog. This can be at the fuel nozzle or the carburetor. It could also be a clog in the air filter or the spark plug, but you have to start with the fuel system.

If you have gas in the fuel tank but the lawnmower engine won't start in spite of that, then the problem is most likely in the carburetor or the fuel line.

A clogged carburetor is a common reason your lawn mower won't start. This part of the engine is responsible for mixing the gas and air before it goes into the cylinder.

If you mix the gas and air in the wrong ratio, you'll end up with a lawn mower that runs rough and can't start. If your lawn mower won't start, it might be time to clean it.

4. A dirty air filter

If you're having trouble starting your lawn mower, there may be an easy solution: clean the air filter. Most gas-powered mowers have air filters that keep dust and other impurities out of the carburetor while the engine is off.

Depending on how often you use the mower, the air filter can get pretty dirty in just a few hours, and it's easy to forget to clean it if you mow infrequently.

A dirty air filter can prevent your mower from running properly, and it can even cause your mower to die completely if it gets too dirty.

It’s a fact of life, air filters need regular maintenance. If you fail to maintain your air filter, you will ultimately harm your lawn mower.

If you don’t know how to clean the air filter on your lawn mower, you may be wondering what is the easiest way to clean a lawn mower filter.

Thankfully, this is a common problem that can be remedied with a few simple steps.

5. Stuck open valves

While most lawn mower problems can be solved by adjusting the carburetor and checking the spark plug, there are times when those measures won't solve the problem.

If you have checked the mower's gas tank and you have the right mixture of gas and oil, you will need to move on to more serious measures. (But don't worry, it's nothing to be afraid of.)

One of the most common serious problems is that the valves are stuck open. When this happens, the engine will not be able to turn over.

If you're having problems with your lawn mower, it's often because the valves are stuck open or closed. The valves are the parts of the lawnmower engine that control the flow of gas and air into the engine.

With stuck open valves, fuel flows freely through the engine, but air cannot. Stuck closed valves block the flow of fuel, but air can still enter the engine. In either case, the engine cannot start.

Last Words

A lawn mower is a large investment that can easily accumulate a lot of money on parts and on fuel, and if you use it every week in your lawn care business, then keeping it running can be worth the effort.

However, there are times when your lawn mower just won't start, and that can be incredibly frustrating.

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My father, and his father before him, and his father; for the past 3 generations, my family have always been into gardening. The green fingers is a gift passed down to me and I thoroughly enjoy it! I also have worked in the manufacturing department for Bosch and DeWalt so I like to think I know a thing or two about tools and such!
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