Lawn Mower On Fire

Seeing a lawn mower on fire in your backyard is a startling and dangerous situation. Your quick response is crucial for safety, and understanding why it happens helps prevent future incidents. Let’s walk through exactly what to do, why it occurs, and how to keep your mowing season safe.

This alarming event is more common than you might think. Most fires start from a combination of heat, fuel, and oxygen—the classic fire triangle. In a mower, the fuel is often gasoline, oil, or dried grass clippings. The heat can come from a hot engine, a blocked exhaust, or a spark. When these elements meet, a lawn mower on fire can be the result.

Immediate Steps to Take When Your Mower Catches Fire

Your safety is the absolute priority. Don’t try to be a hero and save the machine. Follow these steps in order.

Shut Off the Mower: If you can do so safely and without delay, turn the ignition key to “off” or move the engine switch. This stops the fuel pump and electrical spark.
Get Away: Move back at least 30 feet immediately. A small fire can quickly grow if it reaches the gas tank.
Call 911: Don’t hesitate. Explain you have a gasoline engine fire in your backyard. Fire departments would rather respond to a small, controlled situation than a major structure fire.
Use a Fire Extinguisher (If Safe): Only if the fire is very small and you have a clear escape path, use a Class B dry chemical fire extinguisher. Aim at the base of the flames. Never use water on a gas or oil fire.
Alert Others: Make sure family members or neighbors are aware and a safe distance away.

Why Did My Lawn Mower Catch Fire?

Knowing the causes is the first step toward prevention. Here are the most common culprits.

Grass and Debris Buildup: This is the #1 cause. Dry grass clippings, leaves, and twigs collect on the mower deck, around the engine, and near the muffler. The muffler can reach over 500°F, easily igniting this tinder.
Fuel System Leaks: Cracked or loose fuel lines, a faulty fuel filter, or a leaking carburetor can drip gasoline onto hot engine parts. Even a small, steady drip is a major hazard.
Overheating Engine: Lack of maintenance like dirty cooling fins, old engine oil, or a clogged air filter makes the engine run much hotter than normal, potentially igniting nearby materials.
Electrical Shorts: Frayed wiring, a bad ignition switch, or a faulty solenoid can create sparks that ignite fuel vapors or debris.
Improper Fuel Storage: Using a gas can without a proper spout can lead to spills on the mower’s exterior. Fuel vapors are highly flammable.
Spontaneous Combustion: Rare but possible, a pile of fresh grass clippings can generate enough heat internally to ignite, especially if they are left in a bag attached to a hot mower.

Prevention: Your Seasonal Maintenance Checklist

A well-maintained mower is a safe mower. Stick to this routine checklist before and during the mowing season.

Before the First Mow (Spring Tune-Up)

Clean the Mower Thoroughly: Scrape the entire deck, engine casing, and muffler area clean of all old grass and mud. A putty knife works great for this.
Change the Oil: Old oil contains contaminants that increase engine heat. Use the type recommended in your manual.
Replace the Air Filter: A clean filter ensures proper air flow and prevents overheating. Check it monthly during heavy use.
Inspect the Fuel System: Look for cracked fuel lines, loose connections, and signs of leaks around the carburetor. Replace any suspect parts.
Check Spark Plug & Wiring: Ensure the spark plug wire is snug and the wiring harness is intact with no bare wires.

During the Mowing Season (Weekly/Bi-Weekly)

Clean After Every Use: Let the mower cool completely, then tip it on its side (with the air filter facing UP) to scrape the deck clean. This is the single most important habit.
Mow When Grass is Dry: Wet grass clumps and sticks much worse, creating buildup faster.
Allow the Engine to Cool Before Refueling: Never add gas to a hot or running engine. Spills on a hot surface can instantly ignite.
Store Fuel Properly: Keep gasoline in an approved container, away from your house, and out of direct sunlight.

What to Do After a Mower Fire

Once the fire is completely out and the mower is cold, you need to assess the damage. Do not attempt to start it.

Document for Insurance: Take clear photos of the damage. Contact your homeowners insurance provider to see if the repair or replacement is covered.
Professional Assessment: Have a small engine repair shop inspect the mower. The heat can damage critical components even if things look okay on the outside.
Safe Disposal: If the mower is totalled, do not just put it on the curb. Take it to a lawn equipment dealer or a hazardous waste recycling center. They can handle the fluids and metal safely.
Replace Your Fuel Can: If you suspect your fueling pratice contributed, invest in a new, leak-proof can with a automatic shut-off nozzle.

Essential Safety Gear for Your Shed

Being prepared makes all the difference. Keep these items where you store your mower.

Class B Fire Extinguisher: Rated for flammable liquids. A 5-lb model is a good size. Check the pressure gauge annually.
Work Gloves: Heavy-duty gloves protect your hands if you need to handle hot parts or debris.
Safety Glasses: Wear them when cleaning or inspecting to keep debris out of your eyes.
First Aid Kit: Include burn cream and sterile gauze pads, just in case.

FAQ: Lawn Mower Fires

Q: Can a lawn mower catch fire from just being used?
A: Yes, if it has a significant buildup of dry grass. The heat from normal operation is enough to start a fire if debris is touching the exhaust or engine block. Regular cleaning prevents this.

Q: Is it safe to put water on a burning lawn mower?
A: Absolutely not. Water can spread burning gasoline and oil, making the fire much worse. It can also cause a hot engine to crack. Use only a Class B fire extinguisher or let the fire department handle it.

Q: My mower backfired and I saw a small flame from the exhaust. Is this a fire?
A. A occasional backfire flame is usually brief and contained within the exhaust system. However, it is a warning sign. It indicates an engine timing or fuel mixture issue that should be repaired, as it can ignite external debris.

Q: How often should I really clean my mower deck?
A. For prevention, after every mowing session is ideal, especially in dry conditions. At a bare minimum, do a thorough scrape-down every 2-3 uses. It only takes a few minutes.

Q: Can I use a fire blanket on a mower fire?
A. A fire blanket is designed for clothing or small kitchen fires. For a gasoline engine fire, a fire extinguisher is a far more effective and safer tool because it can smother the flames from a distance.

A lawn mower on fire is a serious event, but it’s often preventable. The key is consistent, simple maintenance—primarily keeping the machine clean and checking for leaks. Your vigilance is the best defense. Equip yourself with the right knowledge and tools, and you can enjoy a safe, green backyard all summer long without any unexpected excitement.