Why does my lawn mower start but then die shortly after?

**Fuel Quality**: Lawn mowers require clean, fresh fuel for optimal performance.

Gasoline can degrade over time, especially if it contains ethanol, which can absorb moisture and lead to starting issues.

**Carburetor Function**: The carburetor mixes air and fuel in the correct ratio for combustion.

If it gets clogged with dirt or old fuel residues, it can disrupt this balance, causing the engine to start but then stall.

**Spark Plug Condition**: A worn-out or dirty spark plug can lead to incomplete combustion.

If the spark plug isn’t firing correctly, the engine may start but won’t sustain running.

**Air Filter Blockage**: A dirty air filter can restrict airflow to the engine.

Insufficient air can prevent the engine from running smoothly, leading it to die shortly after starting.

**Fuel Lines**: If the fuel lines are clogged or cracked, fuel delivery to the carburetor can be interrupted.

This can cause the mower to start briefly before it runs out of fuel.

**Oil Level**: Low oil levels can trigger a safety feature in some mowers that prevents them from running to avoid engine damage.

Always check the oil level before starting.

**Choke Position**: If the choke is engaged too much when starting, it can flood the engine with fuel.

Once the choke is disengaged, the engine may die if it cannot handle the excess fuel.

**Governor Issues**: The governor regulates engine speed.

If it’s malfunctioning, it can cause the engine to rev too high or too low, leading to stalling.

**Battery Health (for electric start mowers)**: A weak battery may provide enough power for a brief start but won’t sustain operation.

Ensure the battery is charged and in good condition.

**Temperature Effects**: Cold temperatures can affect fuel viscosity and vaporization.

In colder conditions, fuel doesn’t atomize as well, leading to starting problems that could cause the engine to die shortly after starting.

**Vapor Lock**: In some cases, heat can cause fuel in the lines to vaporize, leading to a temporary blockage that prevents the engine from receiving fuel.

**Safety Features**: Many mowers have safety mechanisms that stop the engine if the operator isn’t in the correct position or if the blade is engaged.

This can cause the mower to die unexpectedly.

**Mechanical Wear**: Over time, internal engine components can wear out.

Worn piston rings or valves can lead to loss of compression, affecting engine performance and stability.

**Fuel Filter**: A clogged fuel filter can restrict fuel flow to the carburetor.

Regular maintenance of the fuel filter is essential to maintain proper fuel delivery.

**Fuel Pump Issues**: If the mower is equipped with a fuel pump, a malfunction can prevent adequate fuel from reaching the carburetor, leading to starting issues.

**Mower Blade Condition**: A dull or damaged blade can create excessive resistance, forcing the engine to work harder and potentially leading to stalling.

**Electrical Connections**: Corroded or loose wiring can lead to intermittent electrical issues, affecting the ignition system and causing the engine to start and then die.

**Exhaust Blockages**: If the exhaust is blocked or restricted, it can cause back pressure that interferes with engine operation, resulting in stalling.

**Environmental Factors**: Grass clippings or debris can obstruct airflow and cooling, causing the engine to overheat and shut down to prevent damage.

**Calibration Issues**: Carburetors may require recalibration after repairs or maintenance.

Incorrect settings can lead to improper air-fuel ratios, causing the engine to start and die.