An outboard kill switch, or engine cut-off switch, stops the engine when its clip or lanyard is pulled, so the boat does not keep running if the operator goes overboard or is thrown from the helm. The same switch is also one of the most common reasons an outboard will not start: if the clip is missing or not fully seated, the ignition is grounded and the engine will crank without firing, or not crank at all on some models.
How it works
On most outboards the switch holds the ignition circuit open while the clip is in place. Pull the clip and the switch grounds the ignition, killing the spark. The lanyard clips to the switch at one end and to the operator’s life jacket, belt or wrist at the other. Wireless systems do the same job with a fob that stops the engine when it moves out of range or goes into the water. On tiller outboards the switch is usually at the front of the motor or on the tiller; on remote-control boats it is on the control box or dash.
The federal rule
Since April 1, 2021, federal rules require the operator of most recreational boats under 26 feet to use the engine cut-off switch, where one is installed, when running on plane or above displacement speed. There are exceptions, such as docking and slow-speed trolling. States can add their own requirements, so check the US Coast Guard and your state boating agency for what applies to you.
Kill switch problems
- No start, no spark. Clip missing, not pushed fully home, or a spare clip of the wrong type.
- Engine stops on bumps. A worn switch or loose clip that breaks contact on impact.
- Intermittent misfire or cutting out. Corroded terminals or chafed wiring that grounds the circuit now and then.
- Engine will not shut off with the clip pulled. A failed switch or broken wire; fix this before using the boat again.
Testing the switch
With the engine off, disconnect the switch leads and check continuity with a multimeter, clip in and clip out. The reading should change cleanly between the two positions. Which state means “run” and which wire colors are used varies by engine maker, so follow the wiring diagram in your service manual. If the switch tests good, inspect the harness for chafing, especially where it passes through the cowling or control box.
Good habits
- Attach the lanyard before starting the engine, every time.
- Carry a spare clip that fits your switch.
- Replace a lanyard that has lost its coil or has a cracked clip.
- Rinse and dry the switch after salt water use and keep the contacts clean.
Related
If the switch checks out and the engine still will not fire, see outboard won’t start and outboard spark plugs. For routine care, see outboard motor maintenance; to compare engines, browse outboard motors and portable outboards.
More guides: outboard steering cable · outboard fuel lines · outboard ignition switch · outboards for canoes.
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