How to Troubleshoot Issues With Your Lawnmower

Having a properly functioning lawnmower is essential for keeping your lawn looking tidy and well-maintained. However, lawn mowers can develop issues that prevent them from working properly. When your mower starts acting up, being able to quickly diagnose and resolve the problem saves you time and money compared to taking it in for repairs. Follow these troubleshooting tips to get your lawnmower back in working order.

Inspecting the Lawn Mower

The first step in troubleshooting lawn mower issues is a thorough inspection of the mower itself. Look for any visible signs of damage, wear or clogging that could be causing problems.

  • Check the underside of the mower deck. Clear away any accumulated grass clippings or debris with a small brush or compressed air. Clogged chutes prevent proper discharge of clippings.
  • Examine the blade for nicks, bending or dullness. A damaged or dull blade can’t cut grass cleanly.
  • Make sure the drive belt is in good condition and properly attached. A loose or worn drive belt will affect power transfer to the blades.
  • Clean any dirty surfaces and check for corroded or cracked parts. Built-up grime and corrosion can interfere with performance.
  • Look for any loose nuts, bolts or attachments. Tighten any loosened fasteners with the proper tools.

Thoroughly inspecting the mower helps pinpoint issues that may be obvious at a glance before moving on to other troubleshooting steps.

Checking the Engine

Engine problems are some of the most common lawn mower issues. If your inspection didn’t reveal any noticeable mower deck problems, focus troubleshooting efforts on the engine.

  • Check the oil level and consistency. Low oil levels or dirty oil can cause overheating and engine damage.
  • Make sure the spark plug isn’t fouled or damaged. Replace if needed.
  • Clean the air filter and replace if it’s overly dirty. Clogged air filters lead to poor engine performance.
  • Check for clogged fuel lines or issues with the carburetor. Clean or rebuild the carburetor if needed.
  • Examine the starter rope for fraying. Frayed ropes may not engage the starter.
  • Test for spark by removing the spark plug wire and grounding it to the engine block. There should be a bright blue spark.

Taking the time to methodically inspect all engine-related systems helps isolate problems before they cause permanent damage.

Troubleshooting Cutting Issues

If the engine appears fine but the mower isn’t cutting properly, the issue may be with the cutting mechanism itself.

  • Ensure the blade is installed correctly and securely tightened. Improper installation prevents clean cuts.
  • Check the bladebrake clutch to make sure it’s engaging properly. The blade should stop spinning a few seconds after releasing the bail.
  • Examine the underside of the deck for blockages preventing the discharge of clippings. Remove any buildup.
  • Adjust the mower height settings. If set too low, the blade may be jamming into turf and obstructing cutting.
  • Sharpen or replace a dull, bent or damaged blade. Dull blades tear grass rather than cutting it.

Taking the time to tune up cutting components often gets an underperforming mower back to peak conditions.

Testing in Operating Conditions

The true test for a troubleshooting effort is putting the mower back into action. Operate the mower and observe it closely.

  • Listen for odd noises that may indicate issues like a failing belt, damaged blade or engine problems.
  • Check if the engine is overheating or vibrating excessively. This may indicate blockages or worn components.
  • Look for signs of continued poor cutting performance. If problems persist, further inspection is needed.
  • Monitor the discharge of clippings to ensure the chutes aren’t clogged.
  • Verify safety features like the bladebrake clutch are working.

Testing under live conditions confirms everything is working correctly before putting the mower back into regular service.

When to Call a Professional

With proper troubleshooting, many common lawn mower issues can be quickly resolved. However, if problems persist and you can’t diagnose the cause, it’s best to seek professional assistance. A small engine repair specialist can:

  • Troubleshoot and diagnose complex issues beyond DIY abilities.
  • Rebuild engines and carburetors.
  • Sharpen blades using precision grinding tools.
  • Replace worn belts, gears and pulleys.
  • Conduct detailed disassembly to remove clogs.

Don’t hesitate to turn to the experts when faced with a perplexing repair. The cost of professional service is often less than continuing to use a malfunctioning mower.

Frequently Asked Questions About Troubleshooting Lawn Mower Issues

What are the most common lawn mower engine problems?

Dirty air filters, bad spark plugs, stale fuel, and carburetor issues are some of the most frequent lawn mower engine problems. Maintaining these components prevents many issues.

Why does my mower vibrate or shake excessively?

A bent or unbalanced blade, a failing engine mount, or a worn belt can cause a mower to shake or vibrate during operation. Inspect and replace any worn components.

Why won’t my lawn mower start?

If the mower won’t start, common culprits include a faulty spark plug, obstruction in the fuel line, seized engine, dead battery on models with electric start, or a faulty starter motor.

What causes surging or inconsistent engine speed?

A dirty air filter, improperly adjusted carburetor, or failing fuel pump can all cause irregular engine RPMs. Check these components first when troubleshooting surging issues.

Why is my lawn mower cutting unevenly?

Uneven cutting often results from a dull, damaged or incorrectly installed blade. A bent deck or hitting obstructions can also alter cutting ability. Inspect the deck and blades.


Troubleshooting and repairing basic lawn mower issues can be done by most DIYers with some mechanical aptitude. First, thoroughly inspect the mower inside and out looking for visible flaws. Check the engine components and perform any needed maintenance. Ensure the cutting components are sharp and undamaged. Finally, test operate the mower to confirm all issues are resolved before returning the mower to regular duty. For major repairs beyond your skills, don’t hesitate to utilize a small engine repair specialist. With some diligent troubleshooting, you can save yourself the hassle and expense of replacing a lawn mower that just needs some TLC to get back up and running smoothly.