When you start a lawnmower, it runs smoothly and effortlessly. But as soon as you start mowing the lawn, the engine starts to backfire, making a loud noise that’s very irritating. This type of lawnmower backfires is caused by fuel igniting outside the engine, usually in the muffler. , The backfire may not hurt your engine, but it’s usually a sign of a mechanical problem. If you know why your mower makes a backfire noise, you can fix the problem and prevent it from happening again, which means you can use your mower as normal. Engine backfires can be unexpected and mostly occur when you turn off or start your engine. Having basic knowledge about backfires and how to deal with them will help you avoid costly repairs.
Why Does My Lawnmower Backfire, and how can I fix it?
Backfires can occur when Sometimes, fuel can leak from your engine’s cylinder before the valves close or during the exhaust stroke and enter the engine or exhaust. If the unspent fuel enters the engine and comes close to the spark, it could ignite, causing a small engine explosion. The best way to reduce the amount of noise produced by your engine is to keep your fuel mixture lean, meaning that the fuel-air mixture isn’t too rich.
Backfire problems in engines are generally caused by simple and basic chemical problems, and fixing them isn’t difficult. It is important to fix the problem quickly to avoid further damage to your engine and exhaust. Lawn mower tips presented in this article will surely help you manage a backfiring situation in a better way.
When does a backfire in lawnmowers occur?
- While starting the lawnmower
- While shutting down
- After shut down
Backfire while starting the lawnmower
It is rare for a lawnmower to backfire while starting. If it happens, it could indicate that the mower’s system is damaged in some way. It’s possible that the lawnmower hit something when you were mowing, and it damaged the flywheel. If the flywheel is damaged, your mower may start stuttering and backfiring.
While shutting down
The backfire might be due to speeding up the mower and this is the most common reason that a lawn mower backfires while shutting down
Backfire after engine shut down
After shut down Most lawn mowers will not backfire as long as the air filter and spark arrestor are functioning properly. It may be due to incorrect carburetor settings, the quality/type of the gasoline being used, and the construction of the muffler. This is a topic worth discussing further.
What is the cause of a Lawn Mower Backfire?
If the engine is properly maintained, it should not backfire. It is also possible that the backfire is caused by something that was not maintained properly. There are several reasons why a backfire may occur.
The air filter is responsible for keeping the engine free of debris. If the filter is clogged with dirt or leaves, the engine will not be able to perform efficiently.
Generally, lawnmowers backfire when the gas mix is too lean. There is more air in the gas mix, and this results in incomplete combustion. The gas that is pushed to the exhaust is still full of gas. When this gas gets to the exhaust, it will explode spontaneously and make a bang. This is the backfire.
why Backfire in a lawnmower and other Small Engines:
Lawn mowers are “small” internal combustion engines. Internal combustion engines are the power plants of the 21st century. They use a combustible gas mixture, such as gasoline or diesel, to produce power. This production of power happens in either 2 strokes or 4 strokes. It’s interesting that, in both cases, Combustion of the air-fuel mixture is the most vital stroke in which a spark ignites the mixture, causing an explosion and, therefore, a release of Fuel is burned in a controlled manner inside the combustion chamber. Combustion or burning of fuel anywhere else will cause a bang, which is called backfire.
Backfiring in lawnmower engines can be caused by either fuel-related causes or engine-related causes. Both are explained below.
Fuel-related backfiring in lawnmowers is caused by one or more of the following:
Poorly mixed fuel (mixture of fuel and air)
When the gas hits the spark plug, it ignites and burns in the chamber. Like any burning gas, combustion requires oxygen. In each engine, the correct air-fuel mixture is provided to the combustion chamber during operation. All strokes are timed to give the maximum amount of power in the shortest amount of time for the most efficient and comfortable operation. When the air-fuel mixture is not correct, it will cause a wide range of problems for your engine. For example, if the fuel is too rich, it could result in your engine blowing smoke.
Improperly adjusted carburetor
The timing of the process is so important that the timing is regulated. Something going on early or getting delayed by some seconds can cause problems. A badly-proportioned air-fuel mixture can cause a timing disturbance.
Poorly maintained fuel injection system.
Too much air in the combustion chamber causes the engine to lack power because if too much air in the combustion the engine will not create a spark. When the ignition is delayed, other processes are keeping going in the way they are supposed to go. This causes the fuel to pool in the low spots along with the exhaust. The ignition system is then used to start a small explosion outside the combustion chamber, which causes a larger explosion. This is called backfire.
Fixing Fuel related Backfire:
Maintained fuel filter.
An air-fuel mixture with more than the required amount of air is called a high-pressure fuel. If your lawnmower is backfiring, the faulty lawnmower may be caused by a malfunctioning fuel filter. Look for any reasons why your engine could have low-pressure fuel. They could include old fuel filters or a fuel pump problem. Replace the old fuel filters and get the fuel pump repaired. These fixes will solve the problem that low-pressure fuel is causing your mower to backfire.
Check the carburetor
The carburetor should be inspected for proper functioning. It should be inspected for dirt and debris. Check to make sure the float bowl and air filter are clean and in good condition. Look for leaks. If there is any leakage or any dirt clean the carburetor.
Engine Related Issues:
As mentioned earlier, the timing of all engine processes is crucial for its smooth function. A backfire is caused by problems related to the timing system, which can cause engine failure.
If yours is backfiring, check for its motor’s timing. If the motor timing is not right, the engine may catch fire before the intake valves close. This can cause a backfire in the engine.
In order to prevent this problem, it is important to keep the timing between the engine and the valve set correctly. This situation inside the engine results in backfires.
Backfire Fix: Engine related
- Engine Tune-up
- spark plug
- Fuel Filter
It’s a good idea to have the engine and the valves checked periodically, as it can prevent the engine from running poorly. Both valves will then open and close at the right time preventing the fuel from getting burned in the engine.
Clean the plug’s wires and the plug chamber. Making this adjustment will ensure that the ignition occurs at the right time and will prevent the backfires that result from mistimed ignitions.
Spark plugs may be damaged due to improper battery charging. If you worried about how to charge the lawn mower battery properly? here is complete guidance and help
If the filter is not working properly, the fuel is not being filtered, which can cause the backfires that are occurring. It is recommended that you replace the fuel filter every two years.
In conclusion, the best way to avoid “Why does my lawnmower backfire?” is to start with a clean engine. If you are using a gas-powered lawnmower, it is a good idea to use a carburetor cleaner to clean out the air filter. This will help to prevent backfiring. If you are using an electric lawnmower, then check and clean the spark plug for avoiding backfires
Frequently Asked Question:
Lawn mower engines backfire due to the following possible reasons:
1. Improperly adjusted carburetor
2. Poorly maintained fuel injection system.
3. clogged Spark plug
The first thing you should do is unplug the mower and remove the blades. You can clean the mower deck with a hose, but you will need to use a vacuum cleaner to clean the underside of the deck. If you are unable to clean the deck, the next thing you should do is shut off the engine. If you don’t, the engine will continue to drain out water that has collected on the engine.
1. Your lawn mower may be misfiring because it has a problem with the spark plug. This is the part of the spark plug that produces a spark that ignites the gas mixture.
2. Too much air in the combustion chamber causes the engine to lack power because if too much air in the combustion the engine will not create a spark
It depends on several factors, including the type of lawn mower, the size of the lawn, the type of grass, the weather, and the time of year. But try to tune the mower once or twice a year to maintain its performance.