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Why Does a Lawn Mower Engine Die When Blades Are Engaged?

Lawns need to be mowed regularly in order to stay healthy. Lawn mowers are designed to do this task in a quick, efficient way and they often come with an engine that can run for many hours without needing a break. 

Lawn mowers use engines to power them. The engine is what provides power to the blades that cut your grass and lift it up. In a nutshell, a lawn mower uses gasoline or propane to turn an engine. 

Unfortunately, the engine will sometimes die which means you won’t be able to use your lawnmower until it’s fixed. There are several reasons behind a lawn mower engine dying when blades are engaged.

In this article we’ll be discussing the reasons and the fixes about the issue. Let’s get started.

Dead lawn mower engine
Dead lawn mower engine

Reasons why lawn mower engine dies when blades are engaged

  1. The engine is not receiving enough gas
  2. The motor isn’t warmed up enough
  3. The clutch not pushed when engaging
  4. Not pushing the clutch far enough
  5. Too much resistance when the blades turning
  6. Something binding in the blade/deck belt path
  7. You are pushing the wrong direction

Improperly Routed Belts

Belts that are routed improperly can cause contact between the engine and the blades, resulting in an engine failure.

poorly routed belt lawn mower
Poorly routed belt

Properly routing a belt will ensure it doesn’t contact anything and will keep the engine running smoothly. In addition to this, it’s important to re-route the belt when needed to prevent future damage. 

Properly routing your belts will ensure that you get a long-lasting lawn mower experience. Just remove the belts and put it back in the right way.

Stuck Pulleys

Pulleys are a type of mechanical device used to transmit motion from one moving object to another. The drive belts drive the pulleys and they turn the spindles.

The engine on a lawn mower will turn the blades when the drive belt is engaged, but if a pulley doesn’t turn freely, it can cause the engine to die. 

A common issue with lawn mowers is that they are not able to spin their pulleys freely when going over an area of grass that has been cut recently. The blades may just be stuck in place and won’t engage with the spindles.

Unstuck the pulleys to fix these issues.

Damaged Safety Switch

Your lawn mower has been made with a safety feature called the seat-switch. This switch will help protect you and you in case of an accident.

Bad Safety Switch of a lawn mower
Bad Safety Switch

A damaged safety switch can be a major cause of engine failure. A safety switch on a lawn mower can cause the engine to die when a blade is engaged. Replacing the damaged safety switch will solve this problem.

Moisture in your gas tank

If your gas tank has some moisture in it, you might have a problem when you start your lawn mower engine. Heavy rains can cause water to get into the gas tank, which will lead to water settling on the bottom of the tank. 

This can cause the engine to die when blades are engaged. Moisture is the culprit when your lawn mower’s engine dies when blades are engaged.

 Due to condensation and settling to the bottom of the tank, gas has picked up water and become unusable. 

When this happens, it usually happens in winter. If you have noticed your lawn mower experiences hard starts and stops, or poor performance, it could be caused by moisture getting in the gas tank and corroding the engine. 

If you notice any other signs of problems with your gas tank, such as fuel leaks or a strange smell coming from it, get it examined right away. Remove the moisture from the gas tanks.

Fouled Carburetor

A carburetor is a device that mixes the right ratio of fuel and air so that an engine can work at its best. It’s purpose is to mix the right amount of fuel and air. The carburetor does this by taking in some air and then adding in a specified amount of fuel. 

Some lawn mower engines have a carburetor that allows air to go into the fuel tank when the engine is running. If the carburetor isn’t set up properly, it doesn’t allow fuel to go everywhere it needs to. 

That’s why adjustments and troubleshooting are important. If there is a clog in the jets or small orifices, will even prevent oil from being able to pass through then this can cause the engine to die after a few minutes of running.

You have to clean your carburetor to fix this issue. Or you might also have to replace the carburetor.

Bad spark plug

Lawnmower engines are designed with an electric spark plug to provide the right amount of energy to start and run smoothly. You will not get all the benefits your lawn needs if you have a spark plug that is not working properly. 

A bad spark plug can cause your lawn mower to run rich or even backfire.

The spark plugs turn on the fuel and air mixture in a cylinder chamber to allow it to fire up. You might need to inspect your spark plug. 

If the end connector assembly is covered in carbon, you can clean it off by rubbing it with a brass wire brush. If it is worn out or damaged in any way, you will either need to clean it or also you might have to replace it.

A man is replacing bad spark plug with a new one of a lawn mower
Replace bad spark plug with a new one

Problem with the grass you are cutting

The problem may also lie in the actual grass that you are cutting. You might need to change the height of your blades if you are mowing in a particularly dense, dry area.

This way of mowing wet grass can be a big problem. If you are not careful when handling wet grass, it will end up wedging itself in the grates or getting caught in the auger blades beneath them. 

This will cause the mower to overheat or take longer to do its job.


The lawn mower might get problems sometimes. Such a problem is the engine dies when the blades are engaged. We’ve discussed the reasons in this article. And some of the possible fixes about the issues. 

Follow the proper way to fix the issue or if you can’t fix by yourself then get a professional or contact your dealer.

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