Gas Walk-Behind Mower: Won't stay running

Fuel system problems often cause the engine to stall, so you'll need to rebuild or replace the carburetor if it won't stay running. Our fuel, ignition and compression problems video provides additional tips for troubleshooting fuel system problems.

Some engines stall if the gas cap vent gets clogged. Check your mower's gas cap and clear the vent if it has one. Tuning up the mower engine may also help keep the engine running as you mow the grass.

gas walk-behind mower

These repairs may help solve your gas walk-behind mower problem

Rebuild a lawn mower carburetor

Rebuild a lawn mower carburetor

A clogged or dirty carburetor causes the engine to run rough or prevents the engine from starting. If you can start the engine using starter fluid but the engine won't continue to run, clogged carburetor jets may be the problem. Clean and rebuild the carburetor using a carburetor rebuild kit if the engine won't start or it runs rough because the carburetor isn't supplying the engine with fuel.

March 1, 2016
By Lyle Weischwill
How to rebuild a lawn mower carburetor

If your lawn mower won't start or runs rough, the carburetor could be damaged or clogged. Follow the steps in this DIY repair guide and video to rebuild a lawn mower carburetor in about half an hour.

Repair difficulty
Time required
 60 minutes or less
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Replace a lawn mower clogged carburetor

Replace a lawn mower clogged carburetor

A clogged orifice or jet in a carburetor prevents the engine from getting the mix of gas and air it needs. When the carburetor is clogged, the engine won't start, runs rough or won't stay running. It's usually more effective and cost efficient to replace the carburetor rather than rebuild it.

March 1, 2016
By Lyle Weischwill
How to replace a lawn mower carburetor

When your lawn mower runs rough or won't start at all, the carburetor might be clogged or damaged. This DIY repair guide and video show how to replace a lawn mower carburetor in 30 minutes or less.

Repair difficulty
Time required
 30 minutes or less
Read more
Tune up a lawn mower

Tune up a lawn mower

Tune up a walk-behind mower when the engine runs rough or won't start. You may need to tune up the engine when it vibrates too much or won't stay running. Regular tune-ups prevent engine wear and improve engine efficiency. A walk-behind mower tune-up includes changing the oil, spark plug and air filter. It could also include sharpening or replacing the blade.

March 1, 2016
By Lyle Weischwill
How to replace a lawn mower spark plug

If your lawn mower engine runs rough or is hard to start, a new spark plug could be the right fix. This repair guide and video explain how to replace a lawn mower spark plug.

Repair difficulty
Time required
 15 minutes or less
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Symptoms for gas walk-behind mowers

Choose a symptom to see related walk-behind mower repairs.

Main causes: drive control cable failure, worn or broken drive belt, bad transmission, broken drive wheel
Main causes: uneven wheel height settings, damaged wheel, dull or damaged cutting blade
Main causes: stale gas, engine needs tune up, bad spark plug, dead battery, bad recoil starter, faulty safety switch, bad ignition coil
Main causes: dirty carburetor, bad spark plug, clogged air filter, engine choke problems, clogged gas cap vent
Main causes: damaged cutting blade, loose cutting blade, damaged flywheel key, engine needs tune up
Main causes: engine needs tune up, dirty or clogged carburetor, damaged flywheel key

Repair guides for gas walk-behind mowers

These step-by-step repair guides will help you safely fix what’s broken on your walk-behind lawn mower.

March 1, 2016
By Lyle Weischwill
How to replace a lawn mower drive cable

The drive cable engages the transmission to spin the drive wheels and move the mower across the grass. Replace the drive cable if it's broken or frozen up inside the sheath.

Repair difficulty
Time required
 60 minutes or less
April 1, 2013
By Lyle Weischwill
How to replace a lawn mower wheel

Learn how replace a damaged wheel on a walk-behind lawn mower—it's a quick, easy fix.

Repair difficulty
Time required
 15 minutes or less
April 1, 2013
By Lyle Weischwill
How to replace a lawn mower safety switch

The safety switch stops the engine when you release the lever on the handle. This repair guide explains how to replace it if it's not working correctly.

Repair difficulty
Time required
 30 minutes or less

Articles and videos common to all walk-behind mowers

Use the advice and tips in these articles and videos to get the most out of your walk-behind lawn mower.

October 1, 2019

Types of walk-behind mower blades video

By Sears PartsDirect staff

Learn about the different kinds of mower blades and how to maintain them.