Lawn Mower Not Turning Over? 5 Common Fixes 2026

A lawn mower not turning over is one of the most frustrating problems heading into mowing season — but in 2026, most causes can be diagnosed and fixed at home with basic tools. This guide ranks the five most common culprits from most to least likely so you can stop guessing and start cutting.

5 Common Causes for Lawn Mower Not Turning Over

1Dead or Discharged Battery

A dead or discharged battery is by far the most common reason a riding mower or electric-start mower won’t turn over, especially after winter storage. This cause applies only to riding mowers and push mowers with an electric-start system — standard pull-cord push mowers have no battery and are immune to this failure. The battery slowly self-discharges when left unused, and one cold season is enough to leave it unable to deliver the cranking amperage the starter motor needs.

Symptoms

• The engine is completely silent when you turn the key — no crank, no click
• The dashboard lights are dim, flicker, or fail to illuminate at all
• The starter motor turns very slowly and then stops (insufficient voltage)

Care Plan

1. Gather your tools and PPE. Put on chemical-resistant gloves and safety glasses before touching any battery terminals.
2. Test the battery voltage with a multimeter. Set the multimeter to DC voltage and probe the battery terminals. A fully charged healthy battery reads 12.6–12.8V. Anything below 12.4V needs charging before further diagnosis.
3. Charge the battery with a smart charger or trickle charger. Connect positive (red) to positive, negative (black) to negative. Charge at a 2A slow rate for the most thorough recovery — fast charging masks weak cells.
4. Retest voltage after a full charge. If the battery recovers to 12.6V or higher, attempt to start the mower. If it only recovers to between 11V and 12.4V after a complete charge cycle, the battery is likely sulfated or has a dead cell. Have it load-tested at any auto parts store (free at most locations) or replace it — a battery that charges to only 11.5–12.0V will not reliably crank the engine and will fail again quickly.
5. Clean the terminals before reconnecting. Battery terminal corrosion is a sulfuric acid residue — with your gloves and eye protection on, apply a baking soda and water paste to neutralize it, then scrub with a wire brush. Rinse with clean water and dry thoroughly. Corroded terminals increase resistance and can mimic a dead battery even when the battery itself is fine.
6. If you need to jump-start the mower from a vehicle: Connect jumper cables in the correct order — positive (red) to mower positive, positive (red) to car positive, negative (black) to car negative, negative (black) to an unpainted metal ground on the mower frame (not the battery negative terminal). Let the car idle — do not rev the engine. Revving causes a voltage spike that can damage the mower’s charging system. Attempt to start the mower, then disconnect cables immediately in reverse order: negative from mower ground, negative from car, positive from car, positive from mower. If the mower won’t start even with a jump, the issue is likely the solenoid or starter motor (Cause 2).
7. Replace the battery if it fails the load test. Riding mower batteries typically cost $20–$80 depending on CCA rating and brand.

Common Mistakes

• Revving the donor car engine while jump-starting. Idle only — a sudden voltage spike from a revved engine can fry the mower’s voltage regulator or charging system.
• Skipping terminal cleaning and assuming the battery is dead. Heavy corrosion alone can prevent enough current from reaching the starter. Clean terminals first before condemning a battery that may still have usable capacity.

2Faulty Starter Solenoid or Starter Motor

The starter solenoid is a high-current electromagnetic switch that bridges the battery to the starter motor when you turn the key. When it fails — due to corrosion, heat cycling, or internal contact wear — it either doesn’t engage at all or engages weakly. If the solenoid tests good but the starter motor itself is burned out or mechanically seized, the engine still won’t crank. These two components are almost always diagnosed together because one can mask the failure of the other.

Symptoms

• You hear a single loud click when you turn the key to Start, but nothing else happens
• The battery is fully charged (12.6V+) but the starter doesn’t engage
• The solenoid makes an audible click but the starter motor doesn’t spin

Care Plan

1. Confirm the battery is fully charged first. A weak battery can cause solenoid symptoms — verify 12.6V or higher before suspecting the solenoid.
2. Locate the solenoid. On most riding mowers it is mounted near the battery or on the firewall, with two large terminals (battery cable and starter cable) and one or two small terminals (ignition signal wire).
3. Test solenoid activation with a multimeter — spark plug wire DISCONNECTED. Confirm the spark plug wire is still disconnected and secured away from the plug. Set the multimeter to DC voltage. With a helper turning the key to “Start,” check for battery voltage on the small signal wire terminal at the solenoid. If the small terminal receives voltage but the solenoid doesn’t click, the solenoid is faulty. If no voltage reaches the small terminal, the fault is upstream — likely a safety switch (see Cause 4).
4. Test the solenoid output terminals — spark plug wire still disconnected. When the key is held in “Start,” battery voltage should appear simultaneously on both large terminals. If voltage is present on the battery-side terminal but absent on the starter-side terminal during cranking, the solenoid’s internal contacts are burned or open. Swap the solenoid ($15–$35 for most residential models).
5. Test the starter motor if the solenoid checks out. With the spark plug wire disconnected, the ignition key removed, and the mower on level ground with the parking brake engaged, locate the starter motor’s large single input terminal (the post the starter cable connects to). Using heavy-gauge jumper cables, briefly apply 12V directly from the battery positive to this terminal for no more than 1–2 seconds. The motor should spin immediately. If it doesn’t, the starter motor requires replacement (parts only: $40–$120 depending on model and brand). If you’re unsure which terminal is the input post or are uncomfortable working near high-current circuits, this step is the appropriate point to call a small-engine technician.
6. Replace the confirmed failed component. Most residential mower solenoids and starters are available at hardware stores or online — always match by mower model and engine brand, not just by appearance.

Common Mistakes

• Testing solenoid output with the spark plug wire reconnected. The engine can attempt to crank and start unexpectedly. Always confirm the spark plug wire is disconnected and secured before turning the key for any electrical test.
• Applying power to the starter for more than 1–2 seconds. The starter motor is designed for brief cranking bursts, not sustained current. Extended direct power application overheats the windings and can destroy a motor that may only need a solenoid replacement.

3Fuel System Failure (Clogged Carburetor or Stale Fuel)

Gasoline begins to degrade within 30 days of exposure to air, and modern ethanol-blended fuels accelerate this process significantly. Old fuel leaves behind a sticky varnish that clogs the carburetor’s tiny jets and passages, starving the engine of the air-fuel mixture it needs to start. This is among the most common causes of a mower that cranked fine last fall but absolutely refuses to start this spring.

Symptoms

• The engine cranks normally (turns over) but refuses to fire and run
• You smell no fuel at the carburetor during cranking, or the fuel in the tank is discolored, cloudy, or smells like varnish
• The mower ran fine after sitting all winter, sputtered briefly, then died and won’t restart

Care Plan

1. Inspect the fuel. Remove the fuel cap and look and smell the fuel. Fresh gasoline is clear to pale yellow with a sharp smell. Old, degraded fuel looks dark, may be cloudy, and smells like turpentine or varnish. If the fuel is more than 30–60 days old, drain it completely.
2. Drain the tank and fuel system. Using a hand pump or turkey baster, remove as much fuel from the tank as possible. Dispose of old fuel properly — auto parts stores and municipal hazardous waste facilities accept it at no charge. Close or clamp the fuel line before disconnecting to prevent additional spillage.
3. Remove and inspect the fuel filter. Most mowers have an inline fuel filter between the tank and carburetor. A clogged or discolored filter ($5–$10) should be replaced whenever you address fuel system issues.
4. Clean the carburetor. For a light blockage with otherwise clean passages, remove the air filter housing, disconnect and clamp the fuel line, remove the carburetor from the engine intake, and disassemble the float bowl. Spray every visible orifice and jet with a high-quality carburetor cleaner. Use a can of compressed air or a thin copper wire (from a wire brush) to gently dislodge varnish from the main jet. Do not use a steel wire or drill bit, as these can enlarge the precisely machined jet openings and cause the engine to run too rich.
5. Refill with fresh fuel and stabilizer. Use 87-octane gasoline with no more than 10% ethanol (E10). Add a fuel stabilizer according to the package directions to protect the fresh fuel for up to 24 months. Reconnect the spark plug and attempt to start. If the engine still won’t turn over or run, move to Cause 4 to check for electrical safety lockouts.

Common Mistakes

• Adding fresh gas to old gas. Stabilizers cannot “fix” gas that has already broken down. You must drain the tank completely before adding fresh fuel, or the varnish from the old gas will instantly clog your clean carburetor.
• Neglecting the air filter. A fuel-soaked or dirt-clogged air filter can choke the engine just as effectively as a clogged jet. Always inspect the filter when servicing the carburetor.

4Faulty Safety Switch

Faulty Safety Switch

Modern mowers are equipped with an interlock system designed to prevent the engine from cranking unless specific safety conditions are met. If a switch is faulty or if you have forgotten one of the steps, the starter will remain completely silent. Common interlocks include the seat switch (riding mowers), the blade engagement (PTO) lever, the brake/clutch pedal, and the bail handle (push mowers).

Symptoms

• The battery is confirmed good (12.6V), but the solenoid doesn’t even “click” when the key is turned.
• The mower cranks only when you shift your weight or jiggle a specific lever.
• You recently hit a large bump or washed the mower (which can dislodge or short a switch).

Care Plan

1. Verify the basics. Ensure the blade engagement (PTO) is OFF, the transmission is in NEUTRAL, and the brake pedal is depressed fully. On push mowers, ensure the bail handle is pulled tight against the main handle.
2. Inspect the seat switch. On riding mowers, look under the seat for a plug that may have come loose. Disconnect and reconnect the harness to ensure a clean contact.
3. Test for continuity. Unplug the suspect switch and use a multimeter set to continuity (the beep setting). The switch should beep when depressed and stop when released (or vice-versa, depending on the model). If the switch state doesn’t change when pressed, it is faulty ($10–$40).
4. Check for wire damage. Look for wires near the mower deck or steering column that may have been pinched or chewed by rodents. Repair any frayed wires with electrical tape.

Common Mistakes

• Permanently bypassing a switch. Never “jump” a safety switch with a wire for anything other than a 30-second diagnostic test. Bypassing these switches creates a lethal risk of the mower starting while the blades are engaged or while someone is not in the operator’s seat.

5Seized or Hydrolocked Engine

Seized or Hydrolocked Engine

This is the most serious cause. A seized engine is physically stuck due to lack of oil or internal breakage. A “hydrolocked” engine is stuck because a liquid (usually fuel or oil) has leaked into the cylinder. Since liquids don’t compress, the piston cannot move, making the engine feel seized.

Symptoms

• The starter makes a loud “thump” but cannot turn the engine.
• You cannot pull the starter rope (push mowers) or turn the top of the engine by hand.
• You find gasoline in the oil or oil leaking out of the air filter (classic hydrolock).

Care Plan

1. Check for Hydrolock (The Easy Fix). Remove the spark plug. Attempt to turn the engine over (pull the rope or turn the key). If a stream of gas or oil shoots out of the spark plug hole, the engine was hydrolocked.
2. Clear the cylinder. With the plug still removed, crank the engine several times to clear the liquid. Clean the spark plug, change the oil (as it is likely diluted with gas), and reinstall.
3. Check for mechanical seizure. If the engine won’t turn even with the spark plug removed, it is likely seized. Check the oil level; if it’s bone dry, internal friction has likely welded the piston to the cylinder wall.
4. The “Breaker Bar” Test. On riding mowers, try to turn the large nut on top of the engine (under the plastic shroud) with a socket and long handle. If it won’t budge with moderate pressure, the engine requires a professional rebuild or replacement.

Common Mistakes

• Forcing a stuck engine. If you feel hard resistance, do not keep trying to jump-start it. Forcing a hydrolocked engine can bend the connecting rod, turning a simple fix into a total engine failure.