Lawn Mower Won't Start: Basic Troubleshooting
A mower that will not start often has a fuel, air, spark, safety-switch, or battery issue.
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Before you startUse only the checks you can perform safely. Disconnect power before homeowner-serviceable cleaning or inspection. Stop when a repair involves gas, exposed wiring, high voltage, a roof, structural components, or anything outside your experience.
Common signs
- Engine cranks but will not start
- Starter does nothing
- Engine starts then dies
Most likely causes
1. Old fuel
Gasoline degrades and can cause hard starting.
2. Dirty air filter
Restricted airflow can upset the fuel-air mixture.
3. Spark plug issue
A fouled or worn plug can prevent ignition.
4. Safety interlock
Seat, blade, brake, or handle switches can stop starting.
Safe checks to try first
- Make sure controls and safety levers are in the correct start position.
- Replace stale fuel following local disposal rules.
- Inspect the air filter and replace it if heavily dirty.
- For battery models, confirm the battery is charged and fully seated.
When to call a professional
Use a small-engine shop if fuel-system cleaning, ignition testing, blade-area disassembly, or internal engine repair is required.
Bottom line
Start with the simplest visible cause, change one thing at a time, and avoid repeated resets or disassembly when a safety device keeps tripping. A recurring problem usually deserves a proper diagnosis rather than a temporary workaround.