To safely remove gasoline from a lawn mower, ensure the engine is off and cool, then choose from three methods: use the fuel shut-off valve if equipped, siphon fuel using a hand pump, or run the engine until it consumes remaining gas. Always wear safety gloves and goggles, work in a well-ventilated area away from ignition sources, and store or dispose of gasoline properly according to local regulations.

Why You Might Need to Drain Gas from a Lawn Mower

Removing gasoline from a lawn mower serves several important purposes. The most common reason is seasonal storage, particularly before winter months when mowers sit unused for extended periods. Gasoline degrades over time, especially in small-engine fuel systems, and stale fuel can clog the carburetor, fuel lines, and injectors, making the mower difficult or impossible to start when you need it again.

Other reasons to drain fuel include preparing a mower for long-term storage lasting more than 30 days, performing maintenance on the fuel system, addressing a flooded carburetor, or managing a mower that will be transported or stored in an enclosed space where fuel fumes pose a safety risk. Draining the tank also prevents potential fuel leaks during transport or storage.

Safety Precautions Before Draining Gasoline

Safety equipment including goggles, gloves, and respirator laid out on a workbench

Working with gasoline requires respect for its flammability and toxicity. Before beginning, gather the necessary safety gear:

  • Safety goggles or face shield to protect eyes from splashes
  • Chemical-resistant gloves to prevent skin contact
  • A respirator or work in open air to avoid inhaling fumes
  • Closed-toe shoes in case of spills

Choose a work location carefully. Perform this task outdoors or in a well-ventilated garage or shed, away from open flames, spark sources, electrical outlets, and appliances that generate heat. Do not work near a lit cigarette, pilot light, or running vehicle engine. Ensure the mower’s engine is completely cool before starting; hot engines increase evaporation and fire risk.

Have an appropriate container ready for the fuel. Use an approved gasoline storage container with a secure lid, never a plastic milk jug or other improvised container. Keep absorbent materials like rags or spill pads nearby in case of accidental spillage.

Method 1: Using the Fuel Shut-Off Valve

Many modern lawn mowers include a fuel shut-off valve on the fuel line between the tank and carburetor. This is the simplest and cleanest draining method if your mower has one.

Steps:

  1. Ensure the engine is off and cool.
  2. Locate the fuel shut-off valve, typically a small lever or knob on the fuel line near the bottom of the tank or along the line toward the carburetor.
  3. Turn the valve to the “off” position (consult your owner’s manual for the correct orientation if unclear).
  4. Place an approved gas container beneath the fuel line connection point.
  5. Carefully disconnect the fuel line from the carburetor or tank by loosening the hose clamp with a screwdriver or wrench, depending on your mower’s design.
  6. Allow gasoline to drain completely into the container. This may take several minutes depending on fuel volume.
  7. Once empty, reconnect the fuel line and tighten the hose clamp securely.
  8. Leave the shut-off valve in the “off” position if storing the mower, or turn it back to “on” when refueling.

If you do not see a fuel shut-off valve on your mower, proceed to Method 2 or 3.

Method 2: Siphoning Gasoline from the Tank

For mowers without a shut-off valve, siphoning transfers fuel from the tank through a tube into a collection container. You will need a hand siphon pump kit, available at most hardware or automotive stores. Never use your mouth to start a siphon when working with gasoline, as it is toxic and poses serious health risks.

Steps:

  1. Locate the fuel filler cap on top of the tank and remove it.
  2. Insert the intake tube of your hand siphon pump into the fuel tank, positioning it as low as possible without touching the tank bottom.
  3. Place the discharge tube into an approved gasoline container positioned lower than the tank opening.
  4. Use the hand pump mechanism (usually a trigger handle or lever) to begin the siphoning action. Follow the pump manufacturer’s instructions, as designs vary.
  5. Once fuel begins flowing, continue pumping until the tank is empty or until you have removed the desired amount of fuel.
  6. When finished, remove the intake tube and replace the fuel cap securely.

Hand siphon pumps are safer and more practical than gravity siphoning or mouth-siphoning, and they give you better control over the process.

Method 3: Running the Engine Dry

If you prefer not to physically drain the tank, running the engine until it consumes all fuel is a practical alternative, particularly suitable for end-of-season storage. This method also helps clear fuel from the carburetor, reducing the risk of buildup.

Steps:

  1. Ensure you are in a safe, well-ventilated outdoor space away from buildings or flammable materials.
  2. Start the mower engine normally and allow it to run at full throttle.
  3. Mow until the engine sputters and stalls as the fuel supply depletes. Do not refuel; let the engine shut down on its own.
  4. Attempt to start it once more; it should not turn over or will start briefly then stall immediately, confirming the tank is empty.
  5. Allow the engine to cool completely before storing.

This method works well for seasonal storage but is less practical if you need to remove fuel urgently or if the mower will not start due to mechanical issues.

What to Do After Draining the Gas

Once the tank is empty, proper handling of the old fuel and preparation for future use are important steps.

Fuel Storage and Disposal: Store collected gasoline in an approved container in a cool, well-ventilated location away from living areas and ignition sources. Follow your local environmental regulations for gasoline disposal; many communities have hazardous waste collection programs or service stations that accept old fuel. Do not pour gasoline down drains, onto soil, or into storm sewers.

Carburetor Maintenance: After draining, some users choose to add a fuel stabilizer to fresh gasoline before refueling. Stabilizers help preserve fuel quality during storage and can prevent carburetor varnish buildup. Follow product instructions for the correct ratio. However, if the mower will be used regularly, stabilizer is unnecessary.

Restarting After Storage: When ready to use the mower again after storing it with an empty tank, refuel with fresh gasoline. If the mower does not start immediately, it may need several pulls of the starter cord to draw fuel through the system. If it still will not start after multiple attempts, consult your owner’s manual or a qualified small-engine technician.

Brief Note: Clearing Gas from a Flooded Carburetor

If your mower has a flooded carburetor—evidenced by fuel leaking from the carburetor or difficulty starting despite having fuel in the tank—a different approach applies. A flooded carburetor contains excess fuel that prevents the spark plug from igniting the fuel-air mixture.

To clear a flooded carburetor without fully draining the tank: turn off the fuel shut-off valve if present, remove the spark plug wire for safety, and pull the starter cord 10 to 15 times without starting the engine. This action draws air through the carburetor and helps evaporate excess fuel. Reinstall the spark plug wire, turn the fuel valve back on, and attempt to start the mower. If flooding persists, the carburetor may require professional cleaning or repair.

For persistent fuel system problems, consult your mower’s owner’s manual or take the equipment to a qualified lawn mower repair service.