Why is My Lawn Mower Backfiring?
Your lawn mower is backfiring because its fuel is not mixed correctly, your spark plugs are faulty, or the air filter is clogged. What causes a lawn mower to backfire is a common question on many internet forums, with many people complaining about loud popping noises when they mow. Understanding why your lawn mower backfires and how to fix it is crucial to avoid becoming one of the 80,000 lawn mower-related hospital visits annually.
Mowrator creates state-of-the-art remote-controlled electric lawn mowers that don't backfire, but we still know a thing or two about why your gas mower may be giving you trouble. We've outlined common causes of backfiring, how to fix them, and the benefits of switching to an electric lawn mower instead.
Key Takeaways
- An improper fuel-air mixture, such as a dirty air filter, stale gasoline, faulty spark plugs, or carburetor problems, typically causes lawn mower backfiring.
- Regular maintenance — like cleaning or replacing the air filter, draining old fuel, and adjusting or replacing spark plugs — can prevent backfiring and ensure smoother engine performance.
- In contrast, electric lawn mowers, such as Mowrator's models, avoid backfiring entirely by eliminating the internal combustion process while keeping the same power you'd expect from a gas mower.
What Causes a Lawn Mower to Backfire?
A dirty air filter, old fuel, spark plug issues, poorly mixed fuel, and high engine temperature may be why your lawn mower is backfiring. Let's cover the common reasons and quick fixes right here.
| Cause | Reason | How to Fix it |
|---|---|---|
| Clogged or Dirty Air Filter | Restricts airflow, leading to an improper fuel-to-air ratio and incomplete combustion | Clean or replace the air filter regularly to ensure proper airflow |
| Old Gasoline | Degraded fuel can cause poor combustion and leave unburned fuel in the exhaust system | Drain the old gasoline, refill it with fresh fuel, and use a fuel stabilizer if you're storing it for long periods |
| Spark Plug Issues | Worn or improperly gapped spark plugs can disrupt ignition timing and combustion | Inspect, clean, or replace the spark plug and set the correct gap as per the manufacturer's specifications |
| Carburetor Problems | Dirty or incorrectly adjusted carburetor disrupts the fuel-to-air ratio, causing misfires | Clean the carburetor, adjust it according to the manual, or replace worn components if necessary |
| High Engine Temperature | Overheating can cause pre-ignition of fuel or stress engine components, leading to backfire | Check cooling systems, avoid sudden deceleration, and ensure proper airflow by cleaning filters |
Dirty or Clogged Air Filter
A dirty or clogged air filter stops air from entering the carburetor, messing with the ratio of fuel and air. The lack of air entering the engine leads to excess fuel and incomplete combustion. This excess can leak out of your mower engine and cause it to backfire.
How to Fix a Dirty or Clogged Air Filter
You can fix a dirty or clogged air filter by replacing it more often. Replace your air filter every 25 hours of use, or clean it thoroughly if it's reusable. When you replace your filter, ensure it does not obstruct airflow to the engine.
Old Gasoline
Old gasoline begins to break down chemically after 30 days. This releases compounds in your engine that disrupt the fuel-to-air ratio. The poor ratio causes premature ignition and can harm the engine or your body if you're not careful.
How to Fix Old Gasoline Issues
The best way to fix old gasoline causing your engine to backfire is to replace it. Start by draining your fuel tank and properly disposing of the old fuel. If you plan to store your lawn mower for a long time, replace it with fresh, octane fuel and a stabilizer.
When you refill your lawn mower with new fuel, run the engine and flush out any remaining gas to avoid further backfiring.
Spark Plug Issues
Your spark plug can cause backfiring if it is damaged or worn, if the spark plug gap is incorrect, or if you have a faulty spark plug. When you try to start your engine while it has spark plug issues, several things can lead to backfiring. For example, a damaged spark plug wire can often lead to a weak spark that might not ignite your fuel in its cylinder.
An incorrect spark plug gap and faulty plug can also lead to poor engine timing during ignition and harm your engine, exhaust system, and flywheel.
How to Fix Spark Plug Issues
You can fix a faulty spark plug causing your engine to backfire by adjusting, cleaning, or replacing it. You may need to change the gap size per your owner's manual for an issue like an incorrect spark plug gap. Another simple fix might be cleaning the spark plug if debris has built up on its electrodes.
If none of those steps fix the issue, then replacing the spark plug might be necessary to stop your engine from backfiring during ignition.
Carburetor Problems
The carburetor is responsible for mixing the fuel and air in the proper ratio for optimal combustion. When there's something wrong with the carburetor, an improper fuel-to-air ratio — either too lean or too rich — results in your lawn mower backfiring.
How to Troubleshoot Carburetor Backfiring Problems
To troubleshoot why your carburetor is causing backfiring problems, inspect it for dust, debris, or misalignment. Carburetor adjustment and cleaning often fix many of the common reasons why your lawn mower's fuel is igniting in the exhaust. Ensure you also repair and inspect the choke, making any necessary replacements or repairs for worn-out parts.
High Engine Temperature
When your engine temperature is high, the fuel in the combustion chamber can ignite prematurely, leading to a lawn tractor backfire. The mixture of fuel-to-air ratio can also cause your lawn mower's fuel to combust in the exhaust system, especially if your valve or gasket is exposed to high temperatures for a long time.
How to Stop Your Overheated Engine Backfiring
Double-check your cooling system's functionality to prevent your engine from overheating. Proper cooling will also help avoid backfiring. If your engine is overheating because of a leaky cooling system, replacing the component that's giving you trouble is best.
What's the Difference Between Backfiring and Afterfiring?
The main difference between backfiring and after firing is when your small engine experiences mistimed ignition. During backfiring, the ignition occurs in the intake system or combustion engine, while after-fire ignition occurs in the exhaust system or muffler. Here's a quick reference table to help you understand whether your engine may be experiencing backfiring or after-fire.
| Backfire | Afterfire | |
|---|---|---|
| Location | Intake or combustion system | Exhaust system |
| Ignition Timing | During combustion | After combustion |
| Cause | Ignition timing, fuel-to-air ratio, valve problems | Unburned fuel in a hot exhaust system |
| Sound | Sharp popping | Loud bang or pop |
| Effect on your engine | May damage engine components | Usually harmless |
Do Electric Lawn Mowers Backfire?
No, electric lawn mowers don't backfire because they lack an internal combustion engine. While modern electric mowers rely on electric batteries and motors, many models, including the Mowrator S1 Remote Control Lawn Mower 4WD, provide power equal to that of a gas mower. The S1 4WD has 4 Beast™ motors and offers all the functionality you love about your gas mower without any chance of backfiring.
Shop Mowrator's range of remote-controlled lawn mowers and accessories today.
FAQs on Why Is My Lawn Mower Backfiring?
Why is my lawn mower making a popping sound?
A lawn mower making a popping sound is often caused by issues such as a dirty or clogged air filter, a faulty spark plug, or problems with the fuel system, like insufficient fuel flow or stale gasoline. Other potential causes include a clogged carburetor, debris in the muffler, or ignition system issues leading to misfires. To resolve the issue, inspect and clean the air filter, replace the spark plug if worn, and ensure the fuel system is free of blockages or old fuel.
Why is my riding mower backfiring?
A riding mower backfires when unburned fuel ignites outside the combustion chamber, often due to a lean or rich air-fuel mixture, improper ignition timing, or clogged components like the air filter or carburetor. Common causes to answer the question, "Why does my riding lawn mower backfire?" include stale fuel, a faulty spark plug, or rapid engine deceleration, which can allow unburned vapors to ignite in the exhaust system.
Back to Top: Why is My Lawn Mower Backfiring
