My lawnmower is leaking gas from the primer button – have you ever faced this problem? If you have a lawnmower at home, you know the importance of every part of it. Among all the parts, the primer button is a crucial one. It is responsible for pumping gas into the carburetor. But when it fails, your lawnmower won’t start.

Gas leakage from the primer button can happen for several reasons. But the most common cause is a faulty O-ring. It seals the assembly between the primer button and the carburetor to prevent gas leakage. Therefore, other reasons can be cracks and damage to the primer button, lousy seals, and breaking in the fuel line.

If your primer button is leaking gas, it's essential to fix it as soon as possible. It will save fuel and prevent dangerous fumes from building up around the lawnmower.

Likewise, there are a few different ways to fix a gas leaky primer button. I will go over them in this blog post. So, if you're having this problem, read on to find out how to fix it!

The Role of Primer Button

The primer button, also known as the primer bulb, is an integral part of a lawnmower engine. If you don’t know about it (though I assume you know it), read on to learn its definition.

There is a tiny red button near the engine base with the word “prime’ written on it. The primer bulb plays a vital role in starting the device.

When you start a lawnmower, the engine needs to suck in a mixture of gas and air. The carburetor mixes these two in the correct proportions. The primer button provides a quick burst of gas into the carburetor. Hence, this quick burst helps to start the engine.

A good primer button prevents the engine from flooding. Usually, the flood of gasoline happens if too much fuel is introduced into the engine at once.

You essentially give the engine a “mini-fuel injection” by pressing the button. It helps to start the lawnmower more easily. Conversely, you will need to press the primer button a few times before starting the engine.

If your lawnmower isn't starting, make sure you press the primer button enough times. It can also be possible that the carburetor is dirty and needs to be cleaned.

Can Primer Button Leak Gas on Lawnmower?

I think you have noticed the primer button on the riding mower already. You should know that it can leak gas if you do not use it properly. Thus, its main function is to bring fuel into the carburetor to start the engine.

When you press the button too many times or hold it down for too long, the gas can leak out or flood the ground. However, there are many other reasons to cause gas leakage from the primer button.

If you get the leakage issues, immediately solve them by using the gardening mower again effortlessly.

The Reasons for Gas Leakage from Primer Button

Many reasons for a gas leak from the primer button on a lawn mower are like these:

The popular reason is the worn-out or damaged O-ring on the primer button. If it is damaged, it will allow air to enter the carburetor. As a result, the engine starts running lean.

The primer button itself can be broken or get cracks. It can be another reason for gasoline leakage from the machine.

The seal between the primer button and carburetor degrades or worsens after some period. It makes way for the gas to penetrate outside.

Maybe you haven’t sealed the gas tank properly. It happens when you have done improper installation of the gas tank. As a result, your lawnmower can leak gas from the primer button.

If the mower has a faulty fuel filter or pump, it can lead to fuel line leakages.

Other possible causes can be a worn-out carburetor gasket, faulty gas block and gas valve, a damaged carburetor, or its float. It is always better to replace the primer button if there is any sign of leaking gas.

How to Stop Gas Leakage from Primer Button

If you have a lawnmower with primer button leakage, you can try several methods to fix it.

You should identify from where the leakage is happening. It can be from the button itself or the connection between the fuel line and the button. Replace the O-ring or seal if the gas leak is coming from the button. When the leak comes from the connection, you may need to replace the fuel line.

In the case of the primer button, always check if there is any damage to the O-ring or seal.

To replace the O-ring, remove the button from the mower fuel line. After removing it, take it apart and inspect the O-ring or the seal. Hence, you can purchase a replacement O-ring at most hardware stores. Then, install it on the button and reattach the button to the fuel line.

Gas leakage from the connection between the primer bulb and the fuel line needs a replacement of the fuel line.

To replace the line, you should disconnect it from the button. After disconnection, please remove it from the garden mower. Then, please take it to a local auto parts store and get a replacement with the same size and type. Lastly, install it and reattach the primer button to the fuel line.

Always ensure the tight seal of anything you install or replace to the device. For example, install and tighten the gas tank securely. Also, you should replace the parts like the carburetor gasket and gas valve if the situation demands.


Are you still thinking, “My lawnmower is leaking gas from the primer button”?

Check the primer button on the mower for gas leakage regularly. It can be a fire hazard and reduce the lifespan and performance of the engine. As soon as you notice it, take care of it, or contact the professionals. Lastly, do not forget the methods for fixing leakage I have mentioned in this article.

Have a happy grass-trimming day!