How to Fix a Backfiring Lawn Mower & How to AVOID it?

How to Fix a Backfiring Lawn Mower

A backfiring lawn mower is a common problem that creates a lot of unpleasantness in the neighborhood. Backfiring can do a lot of damage to the lawn mower, and decreases the life of the machine and this article aims at answering how a backfiring lawn mower can be fixed.

So, How to Fix a Backfiring Lawn Mower? Change the fuel to one with lower alcohol content, you can also adjust the carburetor settings and improve the cooling system of your lawn mower’s engine. If that doesn’t work, open up your engine and check the timing. If not, you may have to replace certain engine components.

Read on while we explain these points in detail, helping you tackle your backfiring lawn mower with ease in the future.

How to Fix a Backfiring Lawn Mower

While owning a lawn mower helps you maintain your lawn easily, there are some occasions when your peace is disturbed by a loud bang, similar to the sound of a gunshot.

However, the most likely source of the bang is your lawn mower backfiring. It can be a nuisance to both the operator and people around, thus needing an effective solution to the problem.

  • During deceleration, gradually reduce the speed of your engine. Do not allow the throttle to rebound to the rest position immediately. Controlling the deceleration will ensure that the mixture does not get lean due to a sudden reduction in fuel flow. 
  • Change your fuel to one with a lower ethanol content. Fuel with high ethanol content is more combustible. As a result, you could have premature explosions outside of the engine chamber while the lawn mower is in operation, which causes the engine to backfire.
  • Changing your carburetor settings can help curtail engine backfire. The carburetor controls the fuel to air ratio of the mix that is then combusted within the engine. Changing the setting to allow more fuel into the engine chamber will ensure that your combustion process is more efficient, while also ensuring that backfires are avoided.
  • Cooling systems must be made better. If your engine is running at hotter than normal temperatures, the combustion process will not utilize the mixture efficiently within the chamber. 

Not only does this lead to poor fuel efficiency, but fuel particles will remain in the exhaust as well. When it comes in contact with hot components like the muffler of the exhaust, this could lead to an ignition outside of the chamber, causing the backfire.

  • The timing of the engine must be checked to ensure proper ignition. If your timing is not proper, this will also lead to inefficient fuel consumption. This can have an adverse effect on the fuel mix within the engine, eventually causing it to backfire.
  • Worn out components like spark plugs, valves, and ignition coil must be replaced if none of the above work. These are the primary components involved in the combustion process of an engine. Worn out spark plugs and ignition coils can disrupt the timing of the engine by failing to ignite the fuel mix, causing the engine to operate very roughly.

Failure of the valve system can also lead to improper fuel intake and exhaust flow, causing the engine to backfire. We have made a detailed article about When to Change Spark Plug on Lawn Mower, you can read that to know whether to change your spark plug or not.

What Causes a Backfire in a Lawn Mower?

The primary reason why a lawn mower backfires is due to the fuel mix being too lean. As a result, there is a high amount of air in the fuel mix, which causes incomplete combustion. When this mix then moves to the exhaust system, the left over fuel spontaneously combusts, causing your engine to backfire.

So what are the causes for a fuel mix to become too lean then? Decelerating your engine too quickly is one of the most common occurrences. Due to the rapid closing of the throttle, the engine’s timing goes out of sync with that of the throttle. This has an adverse effect on the fuel mix, eventually resulting in a backfire.

Lean fuel mixes can also be the result of high alcohol content in the fuel and increased operating temperature. These result in the engine operating outside of its optimum conditions and tend to advance its timing. The resulting out of sync combustion results in your lawn mowers engine backfiring.

The last probable reason for your engine backfiring is the engine tuning itself. The timing may be too advanced or your fuel mix is slightly leaner than normal. This could lead to backfires when specific operators who are not used to these changed settings operate the machine.

How to Avoid your Lawn Mower from Backfiring in the FUTURE?

Preventing engine backfires from occurring does not take specialized care or skilled operation whatsoever. A few basic steps taking care of your lawn mower is all you need.

Regularly service and maintain your lawn mower. Replace internal components of the engine on time and ensure the fuel you use is good quality. These will not only help your engine run smoothly, but will also ensure that the fuel mix is rich enough for optimum combustion.

Another way to avoid a backfiring engine is to not operate it when the outdoor temperature is high. This could cause more volatile fuels to evaporate easily, while also increasing the engine temperature. The combination of these factors can result in the incomplete combustion process while in operation, leading to a backfire.

Does a Backfire Damage an Engine?

No, a backfire does not damage the engine. Despite how terrifying the term may sound, a backfire occurs when the combustion occurs outside of the engine chamber. As a result, it has no direct impact on the engine.

However, it could have a negative impact on your exhaust system in the long run. This is because they are not designed to handle the heat and energy produced from the combustion that occurs during a backfire

Can a Lawn Mower Explode?

Yes, only gas powered lawn mowers have the slight possibility of exploding. Although it is a very rare occasion, it takes multiple factors going wrong at the same time to result in something as bad as an explosion. So what exactly can cause a lawn mower to explode?

— Also read: Is it bad to leave Gas in Lawn mower over Winter?

Due to the hot temperatures of the engine, there is the chance of fires breaking out while in operation. If the fires are not extinguished quickly, it could spread to the fuel tank. Large amounts of fuel can combust very quickly in the tank, which is not designed to contain the release of energy. As a result, your lawn mower can explode.

Related Questions: 

How Dangerous are Lawn Mowers? Lawn mowers are quite dangerous. They consist of fast spinning blades which are meant to cut grass quickly and efficiently. Coming into contact with the blades during operation can result in severe cuts, injuries and even possible death. 

The internal combustion engines operate at high temperatures, with fuel actively being pumped into the engine throughout. A lawn mower can also tip over easily due to its high centre of gravity, powerful engine and small wheelbase. This can crush the driver under the weight of the mower, causing grievous harm which can even be fatal.

What Causes a Backfire in an Engine? A lean fuel mixture is the primary reason for an engine backfire. The fuel mix has more air than the optimum fuel to air ratio, resulting in the incomplete fuel combustion inside the engine. 

When the by-products of the process enter the exhaust system, the remaining fuel spontaneously combusts, causing the engine to backfire. This is characterized by a long pop like bang.

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