It can be incredibly frustrating when your lawn mower abruptly dies while you’re in the middle of mowing the lawn. Suddenly you find yourself unable to restart the mower, leaving your lawn half-finished. While this situation is annoying, the good news is that with some troubleshooting and maintenance, you can usually get your mower running again.
There are a number of common reasons a mower will die during mowing, including running out of gas, spark plug issues, dirty air filters, carburetor problems, and blade obstructions. The first things to check are fuel level, the spark plug, and the air filter. Make sure the fuel tank has adequate gasoline, the spark plug is tightened and debris-free, and the air filter is clean. If the mower still won’t start, inspect the carburetor and blade area. Tap the carburetor to dislodge any stuck fuel and clear any grass clippings from around the blade.
For riding mowers, also check the battery charge level. With basic maintenance and diagnostics, you can often troubleshoot what is preventing the mower from starting. Taking the time to properly inspect the mower will get you back to mowing more quickly. If the problem persists, you may need to take the mower in for service by a small engine repair professional. With some diligent troubleshooting, you can usually resolve common issues that lead to a mower dying mid-mow.
Common Causes For A Mower Dying While Mowing
There are a number of components that could cause a mower to die unexpectedly while cutting grass. Here are some of the most common underlying issues:
Fuel System Problems
Problems with the fuel system are one of the top reasons a mower will stall out. Here are some specific fuel-related issues to look for:
- Empty gas tank – The obvious issue is simply running out of gas. Check the fuel level and refill the tank if necessary. Always start mowing with a full tank.
- Clogged fuel filter – Debris in the fuel filter restricts fuel flow to the engine causing starvation. Replace the filter.
- Stale fuel – Gas that has been sitting too long breaks down and clogs the carburetor. Use fuel stabilizer or drain old gas.
- Faulty fuel pump – If the fuel pump is failing, insufficient fuel reaches the engine. Test pump and replace if needed.
- Obstructed fuel line – Kinks, cracks, or blockages in a fuel line interrupts fuel flow. Check lines and replace any damaged sections.
Engine Problems
Issues with engine components can also lead to abrupt mower death:
- Faulty spark plug – An old or fouled spark plug misfires, disrupting ignition. Inspect plug and replace if worn.
- Carburetor problems – Internal debris or improper adjustment prevents proper fuel-air mix. Clean carburetor jets and check settings.
- Low compression – Worn piston rings or leaking cylinder head decreases compression. Diagnose and repair compression system.
- Sheared flywheel key – A sheared key throws off ignition timing. Replace flywheel key.
Electrical Failure
Electrical problems can instantly stop an engine:
- Dead battery – Insufficient charge in the battery leads to startup failure. Recharge or replace battery.
- Faulty wiring – Frayed or disconnected wires interrupt current flow. Check wiring and repair connections.
- Blown fuse – Electrical overload blows a fuse cutting power. Find overload source and replace fuse.
- Bad solenoid – Broken solenoid disrupts starter current. Test solenoid and replace if defective.
Mechanical Issues
Physical problems with mower components can also bring mowing to a halt:
- Broken belt – Damaged mower deck or drive belt slips or detaches. Replace broken belt.
- Bent or clogged blade – An obstructed blade creates excessive drag on the engine. Remove blade, repair and clean.
- Transmission failure – Internal gear, shaft, or belt failure in the transmission locks up mower movement. Significant repair often required.
- Blade brake engaged – The blade brake sticking on stops the blade and engine. Release brake mechanism.
Diagnosing Why Your Mower Won’t Restart
When a mower dies unexpectedly, don’t just keep frustratingly pulling the starter cord over and over. Take some time to methodically diagnose the potential source of the problem. Follow these troubleshooting steps:
- Check the fuel system – Confirm there is ample gas in the tank and the fuel valve is turned on. Inspect for kinks in fuel line. Replace fuel filter if clogged.
- Test the spark plug – Remove plug and check condition. If fouled or worn, replace plug. Test plug by grounding to engine block while cranking to see if sparking occurs.
- Check battery charge – For riding mowers, use avoltmeter to test battery charge level. If low, try recharging battery. Replace if necessary.
- Inspect visible components – Look for obvious issues like obstructions in mower deck, damaged belts, bent blades, etc. Repair any visible issues.
- Try starting fluid – Spray starting fluid into the carburetor while cranking. If mower starts briefly, fuel delivery issue likely.
- Look for loose wiring – Check for any visibly detached wires or damaged insulation. Repair wiring connections as needed.
If you’ve worked through all these troubleshooting steps and the mower still won’t start, deeper mechanical or engine issues are likely at fault. Contact a small engine repair specialist for assistance.
| Diagnostic Step | Possible Outcomes |
|---|---|
| Check fuel system | 1. Empty tank – fill tank 2. Clogged filter – replace filter 3. Kinked line – repair line |
| Test spark plug | 1. Fouled – replace plug 2. No spark – replace plug/wire |
| Check battery charge | 1. Low charge – recharge battery 2. Dead battery – replace battery |
| Inspect visible components | 1. Clear obstruction in deck 2. Replace damaged parts |
| Try starting fluid | 1. Starts – fuel delivery issue 2. Doesn’t start – ignition issue likely |
| Check wiring | 1. Find and repair loose connections |
Fixing Common Lawn Mower Starting Issues
If your diagnostics uncovered the source of the starting troubles, here are some steps to get your mower running again:
Fuel Related Solutions
- Drain old gas and refill with fresh fuel if existing gas is stale
- Clean out debris-clogged fuel filter or replace if very dirty
- Clear out obstructed fuel lines using compressed air
- Ensure fuel valve is fully open to allow fuel flow
- Replace faulty fuel pump if needed
Engine Related Solutions
- Replace worn or fouled spark plug
- Clean carburetor jets and inlet screen of debris
- Adjust carburetor settings using manufacturer spec
- Test and replace broken spark plug wire
- Replace damaged gaskets or rings leaking compression
Electrical Solutions
- Fully recharge dead battery and replace if no longer holding charge
- Repair or replace broken starter cord
- Tighten loose alternator belt to restore recharge function
- Fix loose, corroded or frayed wiring connections
- Replace blown fuse with one of the proper amperage
Mechanical Solutions
- Replace broken or stretched mower deck belt
- Replace damaged drive belt if slipping or detached
- Clear obstructions and debris from mower deck
- Remove, sharpen, and reinstall damaged mower blade
- Lubricate and free seized lever/linkage connections
- Release stuck blade brake
Preventing Future Breakdowns
While it’s impossible to avoid ever having your mower die unexpectedly, you can reduce breakdowns through proper mower maintenance and operation:
- Change oil regularly – Old oil can clog filters, valves and bearings leading to failure.
- Replace air filter – A dirty air filter restricts air flow, increasing strain on the engine.
- Sharpen mower blades – Dull blades require more engine power to cut, adding wear.
- Check tire pressure – Improperly inflated tires make mowing more difficult.
- Lubricate moving parts – Prevent binding and wear by greasing fittings and joints.
- Use fuel stabilizer – Stabilizer prevents stale gas that can clog the carburetor.
- Check battery charge – Allowing battery charge to get too low will make starting difficult.
- Clear debris buildup – Excess grass clippings under the mower deck increases drag.
- Don’t tip mower – Tip-overs can damage the carburetor bowls causing leaks.
- Avoid impacting objects – Solid objects can bend blades, break belts, and damage components.
When to Call a Small Engine Mechanic
While many issues can be addressed with routine home maintenance, major repairs will likely require the expertise of a professional small engine mechanic. Seek professional service for problems like:
- Damaged piston, valves, or cylinder – Require engine disassembly
- Worn or damaged crankshaft – Needs crank repair/replacement
- Bent crankshaft – Calls for crankshaft straightening/replacing
- Damaged camshaft – Camshaft removal and replacement needed
- Worn ring gear or transmission issues – Transmission may require rebuilding
- Burned-out alternator – Alternator needs replacement
- Damaged mower deck/frame – Could require deck replacement
- Major carburetor overhaul – Carb may need disassembly and rebuild
For issues requiring significant teardowns, engine repairs, or parts replacements, the skills and tools of a professional mechanic are advised.
FAQ
Why did my lawn mower die suddenly while I was mowing?
There are a few common reasons a mower can die abruptly during mowing, including running out of gas, a clogged air filter, faulty spark plug, dead battery, broken drive belt, or hiting an obstruction.
How can I diagnose why my lawn mower won’t restart after dying?
Start by checking basic functions like fuel level, air filter, spark plug, and battery charge. If those check out, look for visible damage, test the starter with spray, and check for loose wiring connections.
What should I do if my mower died because it ran out of gas?
Make sure to fill the gas tank with fresh fuel. Check that fuel is flowing through the lines and carburetor before attempting to restart.
Why does my mower keep dying when the air filter is dirty?
A clogged air filter restricts air intake, causing the engine to stall out. Replace the air filter with a new, clean one.
My mower won’t start after the spark plug fouled, what now?
Install a fresh, properly gapped replacement spark plug. Check that the plug is sparking while cranking the engine over.
Why did my riding mower cut off even though the battery is charged?
Check battery cable connections are tight. Look for signs of corrosion. Battery may need load testing to confirm if replacement is needed.
How can I tell if a broken mower belt caused my mower to die?
Look for signs of cracking, fraying, detachment or missing sections. Spin pulleys to check for slipping. Replace damaged belts.
What if my mower starts with starting fluid but dies right after?
This indicates a fuel delivery problem like clogged carburetor jets or filter. Clean carburetor and replace filter.
Conclusion
In conclusion, experiencing a sudden stall of your lawn mower while mowing can be both frustrating and inconvenient. However, this comprehensive guide offers valuable insights into the common causes of mower issues and systematic troubleshooting steps to get it running again. By addressing fuel system problems, engine issues, electrical failures, and mechanical issues, you can often resolve the problem on your own. Furthermore, practicing preventative maintenance measures can significantly reduce the likelihood of future breakdowns. Remember that while many issues are manageable with DIY solutions, seeking professional assistance is essential for more complex repairs, ensuring your lawn mower remains a reliable companion for your landscaping needs.