How to Fix a Lawn Mower: 5 Common Issues and Fixes

If your lawn mower is no longer cutting it, you don’t have to rush out for a replacement—backyard mechanics can easily solve many common problems. Wondering how to fix a lawn mower? In many cases, dirt, dust and grass can affect operation. A little know-how, a few common tools, and a bit of elbow grease are often all it takes to get your mower back up and running. Read up on the most common reasons your lawn mower is running into issues and how to repair them.

Safety first 

Before you get started on your DIY mower repairs, take a few steps to ensure your efforts don’t end with a visit to the emergency room. 

• Gasoline and oil from your mower are flammable, so keep potential sources of ignition, like cigarettes, flames and hot objects, out of your work area.
• Remove the spark plug—especially when working near the blade—to prevent the mower from accidentally starting. In the case of an electric mower, disconnect the power supply.
• Work in a well-ventilated area to avoid inhaling unhealthy vapors. 

Additionally, be sure to check your mower’s manual for recommendations on push mower repairs that require tilting the mower on its side—different manufacturers have various ways to prevent spills. 

How to fix a lawn mower that won’t start 

Your lawn mower might not start because of one of these two reasons.

1. It needs new gas. One of the most common lawn mower problems is a refusal to start, which is especially prominent in mowers that have sat idle over winter. Gas can lose its combustibility in as little as 30 days. If you have last season’s fuel still in the tank, drain and refill it with fresh gas.
2. The spark plug needs replacement. An engine requires fuel and a spark to start. If new gas doesn’t offer an easy lawn mower fix, check the spark plug. Loose, dirty and damaged spark plugs are often the reason a mower won’t start. You can clean dirty spark plugs, but it’s recommended that you change them at the beginning of every mowing season and after every 100 hours of use.

How to repair a lawn mower with a hard-to-pull or stuck starter cord

For issues with your starter cord, follow these steps to identify and fix the problem.

1. Check the starter cord. A broken or crossed starter cord is a frequent push mower issue. To repair, remove the cord cover, replace or untangle the starter cord and reattach the cover. 
2. Depress the flywheel brake. The bar you hold down when mowing can cause a mower not to start. Make sure the bar is fully depressed before pulling the cord. If that doesn’t fix the problem, you may have to replace the cable that attaches the brake to the engine. 
3. Clean the mower deck. A mower blade that’s clogged with clumps of grass clippings can make the starter cord hard to pull. Carefully clear any debris that might interfere with the blade and get in the habit of cleaning your mower after each use.  

How to fix a lawn mower that loses power while mowing

A dull blade, dirty air filter or grass that is too long are all reasons why your mower may be losing power.

• An air filter is subject to a lot of dust and grime. A dirty air filter is a typical troublemaker and one of the easiest and least expensive DIY mower repairs you can make. Locate the filter and either clean or replace it. 
• A dull blade can leave your lawn mower struggling to power through a lawn, especially if the grass is particularly long or full. Sharpen the mower blade to restore your mower’s mojo.
   
• Trying to tackle too-tall grass can sap a mower’s power. You can remedy this problem by raising the cutting height of the mower.  

How to fix a smoking lawn mower

A smoking lawn mower is alarming, but it often looks more serious than it is. The most common reason for a smoking mower is oil that has splashed onto hot engine parts or the muffler from an overfilled (or sloppily filled) oil chamber. Follow these steps to help quell the smoke.

1. Allow your machine to cool down and clean any spilled oil off the mower.
    
2. Inspect the oil chamber to ensure it’s filled appropriately.
    
3. If filled correctly, examine the oil chamber for leaks.
    
4. Tighten (or replace) the cap on the oil chamber.

Sometimes, smoke is a sign of a more serious issue. If these simple fixes don’t solve the problem, it could be time to seek professional help.

Lawn mower repair advice for excessive vibration 

If a lawn mower is exhibiting unusual or excessive vibrations, a damaged or bent mower part might be the reason.

• A worn belt is often at fault—they’re easily identified by sidewall damage or cracks. It’s an easy fix, and even an amateur mechanic can swap a mower belt out for a new one in a few hours. 
   
• Running over roots, rocks and hardscape can cause your mower blade to get bent, damaged, or off-balance. If your mower is vibrating, balance or replace the blade. In the future, careful mowing can keep you from needing to perform this push mower repair. 

Sticking to a maintenance schedule will help you avoid common mower problems. If you encounter an issue, following these steps can help most DIYers fix a lawn mower without a professional's help (or expense).