How to Drain Gas from Lawn Mower (Empty the Fuel Tank)

Unstabilized fuel deteriorates in as little as 30 days. Stale old gas in a lawn mower results in difficulty starting up, engine surging, and stalling. If you did not stabilize fuel for winter storage, you need to drain the bad gas in your lawn mower and add a fresh one.

To drain gas from a lawn mower, you can use a siphon pump to suck the fuel from the tank or disconnect the fuel line leading to the carburetor and let the gas drain to a collecting pan.

CAUTION! Bad fuel can spew noxious fumes, therefore, work in a well-ventilated area. Ensure you turn off your lawn mower and disconnect the spark plug wire. Petrol is highly flammable, there should be no any open flame near your working area.

How to Drain Gas from Lawn Mower – Steps

To drain fuel from your lawn mower, you’ll need a gasoline siphon hose, a rug, and a collecting container like a metal can or drain pan. Then follow the following steps.

  1. Park your lawn mower on flat ground in a well-ventilated area. This will help the fuel to remain in one place in the tank for easier removal. Tipping your mower can direct fuel into other sections that cannot easily be accessed.
  2. Disconnect the spark plugs wire to prevent the lawn mower from accidentally starting while draining the gas tank. Gasoline is also highly flammable; any single spark can start a fire.
  3. If your lawn mower comes with a fuel line that runs from the gas tank to the carburetor, place the collecting container under the section and disconnect the fuel line so fuel can drain out of the tank.
  4. For a lawn mower without a fuel connector, open the fuel tank cap and insert a siphon hose down into the fuel and its other end into the collecting container placed on the ground next to the tank.
  5. Squeeze the bulb on the siphon hose multiple times until enough vacuum is created in the tube to drain fuel from the tank.
  6. Once all the bad gas has been drained from the mower fuel tank, disconnect and clean your lawn mower carburetor using a carburetor cleaner to remove all traces of contaminated gasoline.
  7. Use a rug to wipe out gas spills on the tank or other lawn mower parts.
  8. Reassemble the carburetor back on the engine, refill the tank with fresh gas and start your lawn mower engine.

How to Stabilize Lawn Mower Fuel (for Storage)

Whether you are storing your lawn mower for winter or any longer than 30 days, you need to stabilize the fuel to protect the fuel system from corrosion, gumming up, and clogging.

A fuel stabilizer works effectively for all fuel types when the gas is fresh. So you may decide to run your lawn mower engine until all the fuel is burnt or drain the remaining fuel from the mower tank. Once you have an empty gas tank, you can add fresh, stabilized gas.

A proper mixing ratio of fuel stabilizer to gasoline is always provided on the fuel stabilizer label. Depending on the type of stabilizer, you may add 1 ounce of fuel stabilizer to 1 or 2.5 gallons of fresh gasoline. Be sure to read the instructions.

Once you have stabilized the fuel, fill it in the tank to 95% capacity. The remaining 5% helps the fuel to expand comfortably in warm weather without spilling. Run the engine so the stabilized fuel can flow into the carburetor and the entire fuel system.

Be sure of the kind of gas your lawn mower use. Fresh unleaded gasoline with an octane rating of 87 or higher and an ethanol content of 10% or less is the right fuel for a lawn mower engine.

Final Thought

According to Briggs and Stratton, a manufacturer of small engines and lawn mower parts, using a fuel stabilizer eliminates the need to drain fuel before storing your lawn mower by keeping fuel fresh for up to 24 months.

Therefore drain gasoline from your lawn mower only if you are adding stabilized fuel for storage or if the current fuel has gone bad and you want to refill with a fresh one.

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