Lawn mower backfires when shutting off: 2 Common reasons and solutions

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Sometimes, when you shut off your lawn mower you will encounter backfires or more accurately after fire. ‘Backfires‘ is understood as the condition of the mower’s engine making a loud noise, exploding during or after shutting down.

Almost backfires happen while shutting down the machine. After fire occurs when the engine has been shut off. Neither is harmful to the engine at all. But they will indicate something wrong with your mower.

The following article is to help you notice this abnormality of the mower. Let’s find out How to fix lawn mower backfires when shutting off? right now.

Why a lawn mower backfires when shutting off

Let’s find out why the lawn mower burns back when it is turned off. We will divide it into two parts: during shutdown and after shutdown. At each moment, there are different reasons why the machine explodes. Please join us to learn to draw experience for yourself.

How to fix a lawn mower backfires when shutting off?

1. Time during shutdown

When you are mowing then turn off the engine but the engine is not responding means you have slowed down the engine too fast. When the engine speed increases too quickly, it pumps out air that flows to the machine’s silencer. The danger here is that this gas can cause an explosion, backfires. To avoid this hazard you need to gradually reduce the speed and keep the engine idling for 10 to 15 minutes before turning off the engine.

Another point that we need to note is that the engine should not be turned off when the engine is too hot. To avoid causing an explosion, we need to increase the airflow into the engine. This will help the engine cool down and cool down quickly.

2. After turning off the lawnmower

The phenomenon of lawnmower burning right after the engine is turned off occurs due to an overloaded carburetor or a problem with the silencer. We need to check if the carburetor is installed correctly or not, the silencer is wrong. Adjusting these two factors will help solve the problem that the machine is likely to cause fire after shutting down.

In addition to the possibility of an error coming from the carburetor or silencer, using the wrong type of gasoline is also a cause of fire and explosion after turning off the engine. 

When using the wrong type of gasoline, the clear alcohol gas will ignite in the silencer causing an explosion that has the opposite effect. In this case we will have to change to a gas with a lower or less alcohol content. This will completely avoid the possibility of the lawn mower burning back after it is turned off.

How to fix this issue?

Once we know the reason why the lawn mower explodes after shutting down, we need to take reasonable steps to eliminate these hazards. Here are a few methods to help you completely overcome these dangers.

1. Do not turn off the machine while it is still hot

We must not let the machine get too hot. To do this, we should not let the machine operate for too long beyond the allowed time. Always make sure the cooling components for the machine are in good working order.

2. Use the right fuel line

It is necessary to choose gasoline suitable for the lawnmower. Gasoline types with less gas or with less gas than normal are the right choice for lawnmowers.

3. Regularly check two parts: the muffler and the carburetor.

Two of the important parts of a lawnmower for smooth and efficient operation are the silencer and the carburetor. We need to check the machine parts regularly and especially these two parts. Because if one of these two parts fails, it will cause a dangerous amount of explosive gas for the user. 

In cases where the silencer is badly damaged, we need to replace it immediately. Never use the lawnmower without a silencer. It will be extremely dangerous if the machine explodes.


1. Can spark plugs cause backfires?

There is the fact that any problem that upsets an ignition system spark can cause backfires. This happens when your spark plugs are old, corroded, or damaged. Also, it could be because unburned fuel is then allowed to enter the exhaust system, then backfires appear.

But it properly is not because of your spark plugs, it can be caused by distributor cap. However, checking your mower carefully and having good spark plugs makes your vehicle run better.

Further reading: How to change a spark plug on a lawn mower?

2. What causes backfire on acceleration?

This reaction occurs when ignition takes place in the intake manifold or exhaust manifold instead of in the combustion chamber. The problem stems from within the carburetor. Low compression, leakage in the fuel tank, poor engine condition, weak or damaged valve springs.

3. How to stop motorcycle exhaust from popping?

There are many ways to help you stop motorcycle exhaust from popping. You can do it this way:

  • Keep a check on the carburetor.
  • Fuel Injector Cleaner
  • Check your Jets
  • Change Fuel Grade. 

4. When a lawnmower backfires, what does it mean?

Backfires occur when fuel ignites outside the engine. They usually happen in the muffler. So, it can make surprisingly loud noises when you mow your lawn. You should shut your lawnmower and look for the reason. 

It will not hurt your mower but it’s the symptom of a mechanical problem.

Final thoughts

The lawnmower is useful machinery for everyone. It helps you to make an attractive lawn easier. However, you may have to face some issues with your mower. But don’t worry, just be patient and you can fix every problem. 

Today’s article is about lawn mower backfires when shutting off. We discussed the reason which causes backfires of lawnmowers and the idea to fix it for you. Backfires may not be a big problem but in some cases, they can damage your lawnmower’s exhaust and engine. Especially with mowers that use gas-powered.

You should pay attention and carefully check the condition of your machine so it can live for extended periods.

Maintain your mower to beautify your property. If you have big problems when repairing, don’t hesitate to contact the professional. Have a nice day!

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