Most small outboards that will not start have a simple cause: the kill switch lanyard is not clipped on, the motor is not in neutral, the fuel tank vent is closed, the fuel line is not connected or primed, or the fuel has gone stale. Work through those first. After that, check the spark plugs, the choke and, on electric-start motors, the battery and connections.
Outboard won’t start: quick checklist
- Kill switch lanyard: the clip must be in place; a missing clip is the most common no-start.
- Neutral: most outboards only start in neutral.
- Fuel tank vent: open it, or the motor starves after a few seconds.
- Fuel line: connections fully seated at the tank and motor; squeeze the primer bulb until it is firm.
- Choke or primer: use the choke or fast-idle procedure in the manual for a cold start.
- Fuel: fuel older than a few months, especially ethanol blends, can stop a small motor.
- Battery: on electric-start motors, check voltage and clean, tight cables.
Won’t turn over
If the starter does nothing, check the battery, the kill switch, the neutral switch, fuses and the starter connections. On a pull-start motor that will not pull, the engine may be in gear, or a seized engine or lower unit could be the cause.
Won’t prime
A primer bulb that will not firm up usually has a failed check valve, an air leak at a connector or a cracked hose. Replace the bulb or line, and make sure the arrow on the bulb points toward the motor.
Won’t run without the choke
A motor that only runs with the choke on is running lean, most often because of varnish in the carburetor’s small passages from stale fuel. Cleaning the carburetor, fresh fuel and a new fuel filter usually fix it; see outboard runs rough. EFI motors do not use a choke and point instead to fuel pump, filter or sensor faults.
Won’t go into gear
Shift cable adjustment, a worn shift linkage or a lower unit problem can stop the motor from engaging gear. Milky or metallic gear oil points to the lower unit; see how to change lower unit oil.
Spark and compression
Remove the plugs and check them for fouling or wear; a wet plug suggests flooding or no spark. A compression test tells you whether the engine itself is healthy.
Prevent no-starts
- Use fresh fuel and a fuel stabilizer for storage.
- Run the carburetor dry or follow the storage procedure before winter; see how to winterize an outboard.
- Keep a spare lanyard and fresh spark plugs on board.
- Follow the service schedule in outboard motor maintenance.
If an older motor needs major work, compare a replacement on our portable outboards page.
More guides: outboard won’t idle or stay running · boat battery keeps dying · outboard primer bulb · ethanol in boat fuel · outboard kill switch · outboard spark plugs · outboard ignition switch.
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