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7 Reasons Why Your Lawn Mower is on Fire. With Helpful Tips

Are you puzzled by the sudden smoke from your lawn mower? Don’t worry; we’ve got you covered. Our in-depth analysis will help you pinpoint the problem and take the necessary steps to rectify it.

Fuel, dry grass, blades, mufflers, leaks, and electrical cause lawn mower fires. Prevent by letting it cool before fueling, mowing damp, inspecting blades, not mowing tall grass, checking leaks, and keeping clean. Caution when operating can prevent fires.

Are you surprised by the smoke signals from your lawn mower? Don’t stop here! We’re about to explore the reasons behind this and provide a step-by-step guide to rectify the issue and prevent it from happening again.


1. Fuel Hazards:

One of the most common causes of lawnmower fires is refilling fuel or oil into a scorching engine that has long been in use. Its muffler can ignite the vapors and set your lawnmower on fire. Before mowing the grass, you must refill the gas and check the oil level.

If you run out of gas while mowing the grass, let the mower sit and cool at least for half an hour before refilling it. After filling the fuel or oil, wipe up any spills. Never store the gasoline container anywhere near the lawnmower.

Never light a cigarette while refilling the fuel or oil into your lawnmower. Make sure your mower is stored away from your outdoor grill.

2. Dry grass gets stuck in the mower deck:

Your lawnmower can catch fire when the weather conditions are blazing hot. When the grass is dry, it gets packed in your mower deck, which increases the risk of catching fire. When the dry grass builds up in your mower deck, it goes into its muffler, which can catch fire, fall out, and set a whole field on fire.

Fire experts recommend wetting the area if you are about to mow dry grass or brush on a hot, sunny day. It is also recommended to mow early in the morning with higher humidity. It is a good idea to avoid cutting on dry, hot, and windy days.

In my 20 years of experience, I’ve found that fuel system leaks, overheated engines, and faulty wiring are the most common reasons for a lawn mower to catch fire. It’s crucial to be aware of these issues to prevent potential fires. Regular inspection and maintenance can help identify these problems early.

Creating a Barrier: The First Step in Mowing

Start mowing around your lawn and create a barrier to cutting in dry and hot weather conditions conducive to fire.

This way, you can prevent fire since a barrier has been created. It is also good to service your lawnmower in the spring, early summer, fall, or between, as the temperature and humidity levels are favorable enough to prevent fires.

3. Metal blades strike rocks:

Your lawnmower’s blade is rotating at a very high speed, and if it strikes against a rock or a stump of a tree, it will cause a spark and ignite dried grass. Even worse, the blade can itself come flying off.

There are five things you must always avoid. Otherwise, the blades of your lawnmower become dangerous.

  1. If you sharpen the blades of your lawnmower too many times, they become thin, worn out, and weak. If you accidentally hit them against a rock or a tree stump, the blades will come off and injure you.
  2. If the blades of your lawnmower are bent, they will be out of balance. They will scalp your lawn and damage your bearings.
  3. If your lawnmower’s blades are broken, they risk entirely breaking off and injuring you. They are also out of balance and will probably ruin your bearings.
  4. If the blades of your lawnmower are cracked, they can come flying off if you unintentionally hit a rock or tree stump, causing property damage or injuring you.
  5. If you alter your lawnmower blades and ignore the strict safety standards observed by the manufacturer, you are at risk of personal injury, property damage, and even death.

4. The grass is left to grow far too high:

High grass creates clippings and particles that will fly up over the deck of your lawnmower and come in contact with its hottest parts, such as the muffler. They can enter the cooling fans and the engine’s hottest parts, causing an ignition. Field grass is entirely different from your lawn grass.

Field grass will grow faster and higher, even higher than your lawnmower deck. It becomes dry only at the top, while lawn grass stops growing any more heightened when it dries out in extreme weather conditions.

If you let your field grass grow too high, you must seek professional assistance to mow it to prevent a fire.

– Fire Chief Sam Baber’s Warning on Dry Grass and Lawnmowers

“A standard lawnmower is not meant for mowing fields,” said Haddam Fire Chief Sam Baber. “Dry grass builds up in the lawnmower deck and gets in its muffler where it can catch fire, fall out, and set a whole field on fire.”

If not used correctly, Baber added, a push lawnmower is just as dangerous as a riding lawnmower.

“If you have high blades of grass, and a fire is just starting and burning right next to the ground, it will burn the bottom of the grass off first, and grass stems will fall toward the flames,” said Mr. Jon Skinner, who oversees fire investigation and recovery for the federal Bureau of Land Management.

“But if the fire is ripping through that grass, it will burn the tops of that grass first.”

5. Fuel vapors around a hot muffler:

The fuel vapors get packed into the blazing hot muffler and catch fire. “The biggest tip is to make sure you turn it off and let it cool for at least two to three minutes,” Springfield Fire Department Captain Paul Byers said.

“Gasoline has a shallow flash point, and the engine is hotter than that flashpoint, and if you are pouring in and splash it onto the muffler or the head of the engine, it is enough to ignite it and cause a fire right there.”

Signs like unusual smells, smoke, leaks, or the engine running hotter than usual can all indicate a potential fire risk. In my 20 years of experience, I’ve learned never to ignore these signs. Early detection can prevent a small issue from becoming a major problem.

Risks of Inadequate Heat Dissipation

Even after hours of your lawnmower being turned off, its heat sensor shows the muffler temperature near two hundred degrees. The engine of your lawnmower generates a lot of heat. If the motor cannot correctly dissipate that heat, it is at risk of bursting into flames.

Your lawnmower engine has cooling fins molded into the block. Clippings of grass, dust, and debris can clog its fins and act like a blanket, holding too much heat close to the engine. The plastic housing or shroud that covers the top of your lawnmower can also trap a lot of dust, enough to overheat the engine.

6. A gas cap leak or sloppy fueling:

The most likely cause of overheating in your lawnmower engine is a leaky gasket in its carburetor. A leaky gasket has the same effects as a lean fuel-air mix. A leaky gasket will create a gap that lets fuel in and air out, leading to a lean mixture.

“The dirty air filter will make an engine struggle even harder; it does not get the air it needs to go through, and it will run hotter than necessary,” Captain Byers said. “The oil being low can also create an overheated condition.” Fuel leaking onto the motor can catch fire.

If you accidentally spill some gasoline on the grass, don’t mow that patch of grass until all of the fuel has dried away, as the engine or muffler can ignite it. Always refuel on a hard floor. Place a plastic container underneath to collect any spillover.

Preventive measures are key to avoiding lawn mower fires. In my experience, regular maintenance, including cleaning and inspection, can prevent most fires. It’s a simple step, but one that homeowners often overlook.

The Impact of Outside Air on the Gasoline-to-Air Ratio

Air leaks cause your lawnmower’s engine to pull in too much outside air. This throws off the gasoline-to-air ratio. When the engine overheats, its parts expand, and all small gaps become large.

The lawnmower fuel line can easily detach from the plastic fuel tank outlet, resulting in a severe fire risk. To avoid this, you must use replacement fuel tank outlets that are redesigned with large barbs intended to hold the fuel line more securely. 

7. A short in the circuit board:

A short circuit is an abnormal connection between two nodes of an electric circuit intended to be at different voltages. This results in circuit damage, explosion, or outbreak of fire.

A typical short circuit type occurs when a battery’s positive and negative terminals are connected with a low-resistance conductor, like a wire.

In riding or pushing lawnmowers, unintentional short circuits are usually caused when the wire’s insulation breaks down or when another conducting material is introduced, allowing charge to flow along a different path than intended.

How a Closed Choke Leads to a Flooded Engine

When a damaged choke inside the carburetor of your electric lawnmower stays closed instead of opening even after its engine starts, this results in a flooded engine that badly needs a little air to breathe. Some lawnmower carburetors have an electronic solenoid that helps in their operation.

If your lawnmower’s solenoid has gone wrong, its engine will get overheated, resulting in flames. Lawnmower engines can be challenging to diagnose when it comes to temperature. You must pay special attention to the temperature monitoring gauge to avoid catastrophic engine combustion.

How to prevent lawnmowers from catching fire?

Fire Chief Mike Harris said you must be prepared before heading out, even if your Spring Cleanup does not involve a controlled burn. “You must build a firebreak, have water available, keep your piles small, and watch for the wind,” Harris advised. “

Carrying a slight, controlled burn through vegetation does not take much. We see it every year. To prevent overheating, you must keep the engine of your mowers clean and tidy. Dust, dirt, debris, and dry grass can enter its vents and block the air intake.

This means that cool air cannot flow to the engine and cool it. It would help if you regularly took your lawnmower’s casing off to clean off all the dust, dirt, debris, and dry grass.

Using Compressed Air for Cleaning

It would be best to use blasts of compressed air, a toothbrush, and a vacuum cleaner to knock off stubborn, sticky debris, bird droppings, etc. If your schedule doesn’t allow you to perform this maintenance, you must seek a professional mechanic’s assistance to do it regularly.

The next step to prevent your lawnmower from catching fire is to check its oil level. A critically low oil level means the lubricant is not circulating through the lawnmower engine properly, creating a lot of friction. The result of friction is heating.

To prevent the friction from bursting into flames, you must shut down the engine, disconnect the spark plug, and then let the engine cool down for at least half an hour; now, you can add enough oil to bring the level up to a sufficient and safe point.

Identifying Damage in Cooling Fins and Shroud

Another critical step to prevent your lawnmower from catching fire is to check the cooling fins and shroud for any damage. The cooling fins and shroud are meant to dissipate the engine’s heat into the airstream if there are any cracks in your cooling fins or shroud.

They will not be able to remove the heat from the engine, ultimately increasing the danger of your lawnmower catching fire. The final step is to check your fuel-air mixture. If the mix is lean, it means there is more air than usual in the combustion chamber of your lawnmower.

More air translates to the fuel’s detonation instead of combustion, creating too much heat. You can fix this by adjusting your carburetor for a mix heavier on fuel. What happened at Equip Expo 2022 was a stark reminder of the importance of these steps.

Identifying Damage in Cooling Fins and Shroud

The prototype Dewalt Ascent battery-powered lawn mower caught fire at the event. This incident highlighted the potential failure in making and designing these machines.

Companies like Stanley, Black & Decker, and Dewalt must ensure that their products, like the Dewalt lawn mower, are safe for use. The Dewalt lawn mower fire at Equip Expo 2022 was a wake-up call for the industry.

To prevent your lawnmower from catching fire, you must:

  • Oil Check: Check its oil level after five hours of use.
  • Oil change: Change the oil after fifty hours of use.
  • Replace the oil foam after twenty-five hours of use.
  • Replace the inline fuel filter after fifty hours of use.
  • Replace the spark plug after a hundred hours of use.
  • Clean the cooling system after a hundred hours of use.
  • Clean the combustion chamber after one hundred to three hundred hours of use.
  • Inspect the spark arrester after fifty hours of use.

Fifteen things you should NEVER do:

  • Discharge chute: Never point the lawnmower discharge chute towards your home, kids, pets, street, structures, or vehicles.
  • Extra rider: Never allow an additional rider on your riding lawnmower.
  • Reverse direction: Never mow with a riding lawnmower in the reverse direction unless necessary.
  • Unattended: Never leave a running lawnmower alone.
  • Safety controls: Never alter, bypass, disconnect, tamper, or remove any safety controls.
  • Tilt: Never tilt a walk-behind lawnmower; ensure you keep all four wheels on the ground.
  • Rain: Never use an electric lawnmower during rain or to mow wet grass.
  • Extension cord: Never use a frayed extension cord.
  • Under the deck: Never put your hands or feet under the deck of your lawnmower.
  • Children and pets: Never allow your children or pets to come outside on the lawn while mowing the grass. Never assume that children will stay where you last saw them.
  • Refuel indoors: Never refuel the gas tank indoors or store your gasoline container indoors. Never add more fuel than you can use within two weeks.
  • Gas container: Never store your lawnmower or gasoline container near an open flame, the pilot light of a water boiler, or a spark.
  • Refill gas: Never refill gasoline containers on your truck bed with a plastic bed liner or inside any vehicle.
  • Gas cap: Never remove the gas cap or add fuel while your lawnmower’s engine is still running. Never over-fill its fuel tank.
  • Mower Fire: High Grass, Hot Exhaust: Never pull off the road into the brush or dry grass with your riding lawnmower as its hot exhaust pipes and muffler will catch fire.

Five things you should ALWAYS do:

  • Safety instructions: Always read, understand, and follow all the safety instructions given in your user’s manual.
  • Sealed gas container: Always store your gasoline in a sealed container with a CSA, FM, or UL label.
  • Spark arrester: Always have a properly working spark arrester on your gasoline-powered lawnmower.
  • Cell phone: Always keep a cell phone handy.
  • Gas container not near: Always place the gasoline container on the ground away from your vehicles before filling.


To conclude this blog post, I would say that accidents and fires occur due to the operator’s negligence. If you read, understand, remember, and follow all the safety instructions provided by the manufacturer of your lawnmower, you will never face a disastrous fire.

To keep yourself, your loved ones, and your precious property safe and secure, you must always be careful and extra attentive while operating a lawnmower.

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  1. Roberto Ferguson says:

    Great video resources included in the article, very helpful to visually understand the risks.

    • Allard Vdhooft says:

      Thank you, Roberto! I’m glad you found the video resources helpful in understanding the risks. Stay safe while operating your lawnmower.

  2. Troy Martinez says:

    It’s crucial to prioritize safety when using outdoor equipment like lawnmowers, thanks for the reminder.

    • Allard Vdhooft says:

      Thank you, Troy Martinez! Safety first! Always take precautions to prevent accidents with outdoor equipment like lawnmowers. Stay safe!

  3. Anna Stevens says:

    How often should I clean my lawnmower to prevent fires?

    • Allard Vdhooft says:

      Anna, clean your lawnmower after each use to prevent fires. Check for fuel leaks, keep blades sharp, and avoid mowing high grass. Safety first!

  4. Harry Hayes says:

    Interesting, I didn’t know all these factors could cause a lawnmower fire.

    • Allard Vdhooft says:

      Thank you, Harry, for your feedback! It’s a crucial topic that many aren’t aware of. Remember to stay safe when operating your lawnmower to prevent fires.

  5. Tyrone Hamilton says:

    This article is very informative, I had no idea so many factors could cause a lawnmower fire.

    • Allard Vdhooft says:

      Thank you, Tyrone! We’re glad you found the article informative. Stay safe with your lawnmower!

  6. Roberto Butler says:

    I never thought about the dangers of refueling a lawnmower, this article was an eye-opener.

    • Allard Vdhooft says:

      Thank you, Roberto! I’m glad the article provided valuable information about lawnmower safety. Stay safe and happy mowing!

  7. Edwin Obrien says:

    I will definitely be more cautious when operating my lawnmower after reading this article.

    • Allard Vdhooft says:

      Thank you for taking the necessary precautions. Safety first! Keep operating your lawnmower with caution to prevent any unfortunate accidents. Stay safe.

  8. Debra Mason says:

    How important is it to follow the manufacturer’s safety instructions when operating a lawnmower?

    • Allard Vdhooft says:

      Absolutely crucial! Manufacturer’s safety instructions are there to ensure the safe operation of the lawnmower and prevent accidents. Always follow them to avoid any potential dangers.

  9. Penny Rivera says:

    I will make sure to check my lawnmower regularly and follow the safety tips provided here.

    • Allard Vdhooft says:

      Thank you, Penny! Regular checks and following safety tips are crucial to prevent lawnmower fires. Stay safe!

  10. Felicia Lambert says:

    Is there any specific training required to operate a lawnmower safely and prevent fires?

    • Allard Vdhooft says:

      Stay safe, Felicia! Operating a lawnmower safely involves simple precautions like fuel tips and brush management. Follow these steps to keep your mower in prime condition and prevent fires.

  11. Mary Fleming says:

    Can regular maintenance of a lawnmower help prevent fires?

    • Allard Vdhooft says:

      Regular maintenance, cooling, and caution are key in preventing lawnmower fires. Stay safe!

  12. Gabriel Foster says:

    Such an important topic to address, thank you for shedding light on lawnmower fire prevention.

    • Allard Vdhooft says:

      Thank you, Gabriel! I’m glad you found the information on lawnmower fire prevention helpful. Safety first!

  13. Amelia Carter says:

    Thank you for sharing these valuable tips on preventing lawnmower fires.

    • Allard Vdhooft says:

      Thank you for your kind words, Amelia! I’m glad you found the tips helpful. Stay safe and happy mowing!

  14. Maxine Mendoza says:

    How common are lawnmower fires and what percentage of them are preventable?

    • Allard Vdhooft says:

      Lawnmower fires are common and preventable. Fuel, dry grass, blades, mufflers, leaks, and electrical issues are key factors. Taking precautions and following safety guidelines can significantly reduce the risk.

  15. Ritthy Black says:

    Is there a specific brand of lawnmower that is more prone to catching fire?

    • Allard Vdhooft says:

      Always ensure proper maintenance, operation, and safety precautions while using any lawnmower. Regularly check for fuel leaks, blade condition, and grass height. Following these steps will help prevent fires, ensuring safety for all.

  16. Fred Davidson says:

    I appreciate the detailed explanations on how to prevent lawnmower fires.

    • Allard Vdhooft says:

      Thank you, Fred! I’m glad you found the explanations helpful. Stay safe while mowing your lawn!

  17. Crystal George says:

    Great tips on how to prevent a lawnmower fire, very helpful information.

    • Allard Vdhooft says:

      Thank you, Crystal! I’m glad you found the information helpful in preventing lawnmower fires. Stay safe while mowing your lawn.

  18. Georgia Williams says:

    Can lawnmower fires happen even with newer models?

    • Allard Vdhooft says:

      Yes, even newer models of lawnmowers can still be prone to fires. By following proper safety precautions, you can prevent any potential accidents. Stay safe while mowing!

  19. Terra Cox says:

    Are there any specific signs to look out for that indicate a fire hazard in a lawnmower?

    • Allard Vdhooft says:

      Always check your oil level before mowing, and let the mower cool after refueling. Avoid high grass and rocks, and ensure proper maintenance to prevent a fire hazard in your lawnmower. Stay safe!

  20. Herbert Martin says:

    What should I do if I suspect my lawnmower is at risk of catching fire?

    • Allard Vdhooft says:

      Always cool mower before refueling. Maintain, clean, and inspect regularly. Avoid high grass, fuel leaks, and blade issues. Prevention is key to fire safety. Stay cautious.