Stuck with a half-mowed lawn because your mower cut out? Or maybe you're still in the garage trying to get it to turn over. There a several reasons why a lawn mower won't stay running, or won't even start in the first place. We're here to help you diagnose and fix those issues so you can cross yard work off your to-do list.
Lawn mower won't start or won't stay running
Gas is empty or has gone bad
Let's start with the basics. Does your mower have gas in it? I know it's like I'm helping you fix a computer by asking you to turn it off and back on, but it happens. If it has plenty of gas in it, the next step is to make sure the gas hasn't gone bad. If it's 3-6+ months old, try adding fuel stabilizer or replacing it.
Battery is not charged or has a poor connection
Next, make sure the engine cranks when turning the key. If it makes a clicking noise, cranks slowly, or doesn't crank at all, your battery could be the issue. First, check for connection issues by wiggling the cables to make sure they're tight. If the terminals have corrosion built up, remove the negative cable and clean them with a wire brush, then reattach the cable and try again. If you have a multimeter, test the battery's voltage by setting it to DC, touching the red probe to the positive terminal, and touching the black probe to the negative terminal. If it reads 12.7 volts or higher, you're good to go, otherwise, it needs to be charged or replaced.
Spark plugs need to be replaced
If the engine tries to turn over at all, the spark plug isn't the issue. Spark plugs are easy to forget about, but they should be changed every season or every 100 hours. If you've recently put new ones in, check if they're loose or need to be cleaned.
Fuel filter is dirty
The fuel filter keeps dirt, debris, and other junk from reaching the carburetor. After a while, that junk starts to collect and restrict the flow of gas. If your fuel filter looks dirty or you haven't changed it in a few years, you might try putting a new one on. They're fairly cheap and are usually an easy change, so it won't hurt to try.
Air filter is dirty
Like the fuel filter, the air filter collects dust and debris that restrict airflow. It needs to be cleaned or replaced regularly for your lawn mower to run at its best. Take the filter out and tap the loose debris off or go over it with a vacuum. If it's too far gone, go ahead and replace it. They're also fairly cheap and easy to replace.
Cutting too much grass
If you're in the thick of it and your lawn mower loses power all of a sudden, you're probably trying to cut too much grass. Take it a little slower or raise the deck up a touch and see if it helps. It'll take longer, but your lawn mower will thank you.
Underside of deck is clogged up
Does your mower run fine until you engage the blades? If so, your deck may be clogged up. Take a look underneath the deck while the mower is off and make sure no grass or debris is stuck. Wash it out if it's full of junk.
Grass is not cutting evenly or is turning white or yellow
Blades are dull
Dull mower blades will rip grass instead of cutting it. Ripped grass looks uneven and is more susceptible to disease, which can cause it to turn white or yellow. Check if your blades are dull and sharpen or replace them as needed.
Trying to cut too much grass
Cutting too much grass at once will strain your mower and prevent it from cutting like it's supposed to. Ease up on the throttle and take things a little slower to ensure you don't miss any spots. If the grass is tall, make sure your mower is set to discharge or bag instead of mulching.
