March 25, 2021

How to keep lawn mower gas from going bad

Keep gas in your lawn mower from going bad.
Keep gas in your lawn mower from going bad.

Stale gas in a lawn mower could cause the mower to sputter or hesitate, or keep the mower from starting. These simple tips explain how to ensure the gas remains fresh.

Looking for more lawn mower repair guides, tips and troubleshooting advice? Check out our specialized DIY repair help for walk-behind mowers and riding mowers.

Hi, Wayne here from Sears PartsDirect. Our video shows you a few quick tips for storing lawn mower gas. Your lawn mower might not run smoothly — or might not start at all — if the gas is stale or contaminated.

  1. Use a plastic gas can, not a metal one, to store fuel. Rust inside a metal gas can will contaminate the fuel, and contaminated fuel makes the engine hard to start. If the mower does start, it may sputter and die.

  2. Gas begins to get stale about 30 days after you pump it. Use a small gas can and buy less at a time. For a push lawn mower, a 2-gallon gas can should be big enough. For a riding mower, a 5-gallon gas can should be big enough.

  3. If the gas is going to be around for a while, treat the can of gas with fuel stabilizer. Fuel stabilizer keeps gas from absorbing water and going bad. Follow the label directions and mix the correct amount of stabilizer to fuel ratio in a gas can. Never pour fuel stabilizer directly into the mower gas tank.

  4. If you didn’t use a fuel stabilizer, don’t leave gas in the tank when you store it at the end of mowing season. Instead, use it up before you put it away.

Check out our DIY section for more repair tips and help.

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