Lawn mower won't start after a long winter? Clogged air filters or bad spark plugs may be to blame for lawn mower problems at start of the mowing season.
The return of warm weather signals lawns to come out of dormancy and spring into action. But if your lawn mower won't start, you could quickly drown in a knee-high sea of green grass.
Dan Hale, owner of Broad Ripple Lawn Equipment in Indianapolis, says most mower problems are the direct result of failure to perform routine lawn mower maintenance at the end of the mowing season, before storing for winter.
"People don’t really address the standard maintenance issues that are important to keep a mower running," he says. "It’s a piece of equipment that nobody wants to own for a job nobody wants to do."
MORE: How to Tune Up and Maintain a Lawn Mower
A variety of problems can arise over the winter for your lawn mower. Repair pros say cold temperatures cause ethanol-based fuel to gel up, which can clog the carburetor and prevent your mower from starting.
Add to that the potential for clogged, broken or corroded components, and it can be difficult to know where to start.
For those who don't like getting grease under their fingernails, Hale recommends a professional lawn mower tune-up, which involves replacing the spark plug and air filter, sharpening the mower blades and changing the oil and gasoline.
Good to know, but if you find yourself with a lifeless mower at the moment, try these tips.
![Plastic gasoline can](https://webcf.waybackmachine.org/web/20210815103643im_/https://media.angi.com/s3fs-public/styles/structured_-_full_width_image/public/gasoline-can.jpg?itok=m9UwBi75)
Old gas is often the reason your lawn mower won't start in the spring. (Photo by Katelin Kinney)
Check mower's gasoline
Is it the same gas you used last year? If the gas is older than 30 days, empty it from the mower and start fresh.
"The biggest problem that people have is leaving old gasoline in the mower," he says. "Over the winter months [gasoline] loses volatility — then, in the spring when they try to start it, they have a problem."
To prevent old gas from keeping you from your lawn-cutting duties, completely drain the gasoline at the end of each mowing season.
Oil should be measured and checked
Each mower is different, but you should measure the amount of oil and check color consistency. Change the oil if it appears dark black.
Consult your manual for recommended time frames for your mower, but it's normal to change lawn mower oil after 25 to 50 hours of use.
Don't forget your mower's air filter
Clean or replace your lawn mower's air filter annually. A new air filter typically costs $3 to $10. Something as simple as a clogged air filter can compromise the entire mower.
"If they don’t clean their air filter, it fills up and the unit runs more inefficiently," Hale says. "Then you get carbon building up on the cylinder and the spark plug to the point it will cause the spark plug to foul and not work."
Mower's spark plugs could be disconnected
Your lawn mower won't start if the spark plug becomes disconnected. A new spark plug costs around $5.
Be aware that a new plug will often come pre-gapped to match your specific engine. You can use a spark plug gauge to verify that it matches the manufacturer's specifications.
Editor's Note: This is an updated version of a story that originally posted April 4, 2012