Your Mower Probably Isn't Broken. The Gas Is Just Old.

Quick answer: If your mower sat all winter with gas in it, drain or run out the old fuel and refill with fresh gas no more than 30 days old. Check the oil, prime it three times, hold the bar and give one firm pull. That fixes more "dead" mowers than any repair shop will admit.

It's the second Saturday of April. The grass is ankle-high, your husband's on a work trip until Thursday, and you've pulled the cord eleven times. Your shoulder hurts. The mower coughed once on pull six and hasn't made a sound since.

The machine is fine. The gas in it's from last September.

Why old gas kills a good engine

Most pump gas in the U.S. is E10, which is up to 10 percent ethanol. Ethanol pulls moisture out of the air, and gasoline starts losing the light, easy-burning parts that help a cold engine fire. Leave it in a tank for a few months and you've got stale fuel that won't ignite well. Leave it longer and it gums up the tiny passages in the carburetor.

Engine makers like Briggs & Stratton tell you to use fuel within 30 days unless it's treated with a stabilizer. Most people have never heard this. They fill a five-gallon can in May and are still pouring from it in August.

So before you load the mower into the minivan and drive it to a shop, do this:

• Smell the gas in the tank. Sour or varnish-like means it's gone.
• Siphon or tip the old fuel into an approved container. Your local hazardous waste drop-off or many auto parts stores will take it.
• Refill with fresh gas and try again.

If it fires, you just saved yourself a repair bill and a two-week wait in peak season.

Fueling it right

Two rules cover almost everything.

Never use E15 or higher. Some stations sell E15 (it's often labeled "Unleaded 88"). It isn't approved for lawn equipment, and the pump usually says so in small print. Stick with regular E10, or ethanol-free gas if a station near you sells it.

Know which engine you have. Your push mower is almost certainly a four-stroke engine. It takes straight gas in the tank and oil separately in the crankcase, the same idea as your car. Your string trimmer and leaf blower are probably two-stroke. Those need oil mixed into the gas at a ratio printed on the tool or in the manual, often 50:1. Put straight gas in a two-stroke and you can seize the engine in minutes. Put mix in your mower and it'll smoke and foul the plug.

Keep two clearly labeled cans if you run both. A strip of colored tape around the mix can saves a lot of grief.

A few habits worth building:

• Fill the gas can on the ground at the pump, never in the trunk or truck bed. Static can spark a fire.
• Refuel with the engine off and cooled for a few minutes. Gas on a hot muffler is how garages burn down.
• Buy small. Two gallons you'll use this month beats five you'll still be using at Labor Day.
• Add fuel stabilizer such as STA-BIL to the can the day you buy the gas, not the day you remember it.

If you mow a small yard and hate dealing with gas cans, premixed canned fuel like TruFuel is ethanol-free and keeps a long time. It costs a lot more per gallon. For a quarter-acre lot it can be worth it. For two acres, it isn't.

Starting it without wrecking your shoulder

Most walk-behind mowers start the same way. Check yours against the sticker on the engine.

1. Check the oil. Pull the dipstick, wipe it, push it back in, pull it again. It should read between the marks. Running a mower low on oil is the fastest way to ruin it for good.
2. Prime it. If there's a rubber bulb, press it three times firmly. If there's a choke lever, set it to choke. Many newer mowers handle this for you and have neither.
3. Hold the bar. That bar on the handle is a safety stop. The engine won't run unless you're holding it against the handle.
4. Pull slowly first, then fast. Draw the cord out gently until you feel it catch and resist. Then give one smooth, quick, full-length pull. Speed starts the engine. Strength doesn't.

Smell gas and it still won't fire? You've probably flooded it from too much priming. Walk away for 15 minutes. Don't prime again, and try once more.

This is the part people get wrong. Yanking ten times in a row harder and harder floods the engine and strains your back. Three good pulls and a pause will get you further than twelve angry ones.

The two-minute check before every mow

Do this before you start, every time. It takes less time than finding your earbuds.

• Oil level on the dipstick.
• Walk the yard and pick up sticks, toys, dog leashes, the stray Lego. A mower blade throws a rock hard enough to break a window or an ankle.
• Closed-toe shoes. Sneakers at minimum, boots better.
• Eye protection and something for your ears. Mowers are louder than they seem after an hour.
• Kids and pets inside or well away. The American Academy of Pediatrics recommends children be at least 12 before running a push mower and 16 before a riding mower, and says no child should ride along as a passenger. Hold that line even when they beg.

If you've got a 12- or 13-year-old who's ready, teaching them to mow is one of the better things you can hand a kid. It's real responsibility with visible results. Teenagers who don't say much will still take pride in a straight stripe, and the quiet ones are still listening when you teach them something useful.

Once a season, before the first cut

You don't need to be mechanical for any of this. You need a free Saturday morning and about thirty dollars of parts from the hardware store. Bring your mower's model number, printed on the engine or the deck.

Change the oil. Run the mower for a few minutes so the oil warms and flows. Shut it off, then drain it through the drain plug, or tip it to pour out the fill tube if there's no plug. Refill with the type in your manual. Many mowers take SAE 30 or 10W-30, but check yours.

Swap the spark plug. Pull off the rubber boot, unscrew the plug with a plug socket, thread the new one in by hand, then snug it. They're cheap. A fresh one fixes a lot of hard starting.

Replace or clean the air filter. Paper filters get replaced. Foam ones can be washed, dried and lightly oiled.

Sharpen the blade. A dull blade tears grass instead of cutting it, and torn tips turn brown a day later. Pull the spark plug wire first, every single time, so the engine can't fire while your hands are under the deck. When you tip the mower, keep the spark plug side facing up so oil doesn't run into the air filter. Plenty of hardware stores will sharpen a blade for a small fee if you'd rather not do it yourself.

Put this on the list you work from on the Sunday hour that runs your whole week in late March, and you'll never meet a dead mower in April again.

Mowing so the lawn looks good

• Cut no more than a third of the blade at once. If the grass is six inches tall, take it to four, not two. Scalping stresses the lawn and invites weeds.
• Mow dry grass. Wet clippings clump, clog the deck and leave a mess.
• Go across slopes with a push mower, up and down with a rider. Riders can tip on side hills.
• Never pull the mower backward toward your feet if you can avoid it. Look behind you first when you have to.
• Change direction every few mows so the grass doesn't lean one way.

At the end of the season

Either run the tank completely dry, or fill it with stabilized fresh gas and run the engine five minutes so the treated fuel reaches the carburetor. Then scrape the caked grass from under the deck with a putty knife and store the mower somewhere dry.

That one hour in October is why it'll start on the first pull next spring.

When to call someone

A cracked deck, a bent crankshaft from hitting a stump (the mower shakes hard and the blade wobbles), or a carburetor that's still gummed after fresh fuel. That's shop work. And if your season is a newborn, a move or a husband on long deployment, paying a neighborhood teen or a service is just good sense. Sorting out when to hire help isn't giving up. It's running the house well.

One last thing, from the old rules. If you borrow a neighbor's mower while yours is in the shop, bring it back with a full tank of fresh gas and the deck scraped clean, even if it came to you half-empty and caked with last week's clippings.

That's how you get handed the keys again.