Your Mower Sat All Winter and Now It Has Opinions

Quick answer: Most spring no-starts are stale gas gumming up the carburetor. Fresh fuel, a new spark plug and a clean air filter fix the majority of them. Do the job a couple of weeks before your first mow, not the morning of.

What the box says

Check oil. Add fuel. Prime. Pull. Mow.

Five words. Very confident. Written by somebody whose mower has never spent five months next to a bag of potting soil and a bicycle nobody rides.

What you will actually need

• Fresh gas in a clean can. Buy it the day you do the job.
• Fuel stabilizer, like STA-BIL or Sea Foam, for that fresh gas.
• An approved gas container for the old fuel, plus a cheap siphon pump.
• A new spark plug matching the number on the old one or in the manual.
• A spark plug socket and ratchet. A regular socket won't do it, because the plug sits deep and the rubber insert in a plug socket is what keeps you from cracking the porcelain.
• A new air filter, or soap and water if yours is foam.
• Engine oil in the weight your manual lists. Often that's SAE 30.
• Rags. More than you think.
• Carburetor cleaner spray.
• Work gloves, because the blade is sharp even when it's dull.
• The manual. This is the thing everybody forgets. If you tossed it in 2019, search the model number printed on the deck and download it. That way you won't be driving back to the store because the plug you bought was for a different engine.

The steps

1. Pull the spark plug wire off the plug and tuck it away from the plug. Do this before you touch the blade, the deck or anything underneath. A mower can kick over when the blade turns by hand.

1. Roll it outside. You'll be working with gasoline, so stay well away from the water heater, the furnace and anything with a pilot light. Never run an engine inside a garage or shed, even with the door open. Carbon monoxide doesn't care about your plans.

1. Get the old gas out. Siphon it into the approved container. Take it to your local household hazardous waste drop-off. It doesn't go down a drain or into the yard.

Last October my wife asked if I wanted to add stabilizer before putting the mower away. I said it'd be fine. The smell coming out of that tank says she won that one.

1. Check the oil. Wipe the dipstick, reinsert it, read it. If the oil looks dark or gritty, change it. If you tip the mower to drain or work underneath, keep the spark plug and air filter side facing up. Tip it the other way and oil runs into places it shouldn't be.

1. Replace or clean the air filter. Paper filters get replaced. Foam ones get washed in warm soapy water, dried completely and lightly oiled if the manual says so.

You'll find a mouse nest in here roughly as often as you'll find the filter. The mouse had a better winter than you did.

1. Replace the spark plug. Check the gap against the manual, often around 0.030 inch. Thread the new plug in by hand first so it doesn't cross-thread, then snug it with the socket. Don't crank it down like you're mad at it.

1. Deal with the blade. Wearing gloves, check for nicks and bends. A sharp blade cuts grass. A dull one tears it, and the tips go brown and ragged a few days later. Sharpen it or replace it. If you're not confident balancing a blade, replace it.

This is the step where you find out what you ran over in August.

1. Add fresh gas with stabilizer mixed in. Fill to the line, not the brim.

1. Reconnect the plug wire. Now and not before.

1. Prime and pull. Press the primer bulb the number of times the manual says, usually around three. Set the choke if your mower has one. Hold the bail bar, plant your feet and give the cord a smooth, steady pull. Don't yank it like you're starting a chainsaw in a movie.

If it fires on the second pull, go tell somebody. They won't care, but you'll feel better.

Where it goes wrong

It starts, runs ten seconds, then dies. Classic stale-fuel damage. Gas left in the carburetor all winter evaporates and leaves a varnish that clogs the tiny jet the fuel passes through. With the plug wire off, spray carb cleaner into the air intake, or remove the float bowl under the carburetor and clean it out. Many mowers have a bowl nut with a small fuel passage drilled through it. Run a thin wire through that hole and spray it clean. If it still surges or dies, the carburetor needs a rebuild or replacement.

Big cloud of white smoke on startup. Somebody tipped it the wrong way and oil got into the cylinder. Usually that somebody is you. Let it run outside and it'll burn off in a few minutes. If it keeps smoking after that, or won't turn over at all, the plug may be fouled with oil. Pull it, clean or replace it, and try again.

The cord won't pull, or it barely moves. Plug wire off, then check underneath. Dried grass caked into the deck can jam the blade. Scrape it out. Also make sure you're actually squeezing the bail bar. On most mowers the bar releases the blade brake, and without it the cord fights you. My nine-year-old pointed this out while I was rehearsing a speech about how they don't build them like they used to.

When to call a pro

Call a small engine shop if the carburetor rebuild is beyond what you want to tackle, if the mower vibrates hard after you've replaced the blade (a bent crankshaft from hitting a stump or root will do it), or if it's leaking fuel from anywhere. Repair shops get slammed the first warm weekend of the year, so book early.

Timing depends on where you live. In the South, grass starts growing weeks before it does in the northern states or Canada. Check your hardiness zone and plan this job a couple of weeks before your first mow. That first mow is one of the four moves a year your lawn actually needs, and it goes much better with a sharp blade.

One more thing. If you end up borrowing the neighbor's mower while yours sits at the shop, return it with a full tank and the deck scraped clean. Even if it came over half empty and caked with clippings. And this fall, add the stabilizer when somebody you love suggests it.