Converting a Pull-Start Outboard to Electric Start: What It Takes

Kits are matched to the model, the year range and sometimes the serial number range. The plate is usually on the clamp bracket or the swivel bracket. Write down the full model code and serial number. "A 15 hp from the 1990s" is not enough to order the right parts.

Call a dealer for your brand with the serial number and ask three questions: Is there an electric start conversion kit? Which harness or control does it need? What else must be added (charging coil, rectifier, flywheel)? Tohatsu, for example, lists separate electric starter kits for tiller-handle and remote-control engines, which tells you the control setup matters. Some brands list conversion kits only for certain model years, and many older kits are discontinued.

Clues your motor was built to accept one: threaded starter mounting bosses on the powerhead, a flywheel with gear teeth around its rim (the ring gear), and a sister electric-start model of the same horsepower and year. If the dealer says no kit exists, stop here. Homemade conversions with unmatched parts rarely end well.

Make a full list before you decide:

• Starter kit (starter motor, bracket, relay or solenoid, small parts)
• Charging parts if your motor has none (see step 4)
• Start button or key switch harness, or a remote control box and cables
• Cranking battery, battery box and cables
• Dealer labor, often several hours

Add it up and compare with selling your motor and buying the electric-start version, used or new. On a tired motor, that comparison often favors replacing it. See Repower Planning.

A starter drains the battery, so the motor needs a way to recharge it. Many pull-start motors have no charging coil at all, or only a lighting coil that makes AC current. Tohatsu explains that its alternator kit gives a manual-start model 12-volt power, but that power is AC and needs either a regulator (for lights) or a rectifier kit (for charging a battery). On many electric-start models the alternator is standard while it is optional on the manual versions.

Without charging, you would have to recharge the battery at home after every trip. That works for a kicker or a short outing, but plan for it.

Ask how much the charging system puts out, too. Small outboards make only modest charging current; Mercury, for example, promotes the 17-amp alternator on its newer 25 and 30 hp electric-start models as enough to keep starts reliable while running a couple of depth finders. An older small motor's lighting coil may make much less, so a big fishfinder, livewell pump and lights can drain the battery faster than the motor refills it.

Electric-start outboards have start-in-gear protection so the starter will not engage unless the shifter is in neutral. Your conversion must keep this.

• Tiller motors: the kit or harness usually uses a neutral switch on the shift linkage, plus a start button on the tiller or a key switch.
• Remote steering: the remote control box should have a built-in neutral safety switch. Tohatsu warns that a box without one can let the engine start in gear. Do not reuse an unknown box from another brand unless the dealer confirms it is compatible. See Remote Control Box Service.

Keep the kill switch lanyard working with whatever control you choose. See Kill Switch Lanyard.

Use the battery type and minimum rating your owner's manual lists for the electric-start version of your motor. Put it in a strapped-down, covered battery box near the stern so the cables stay short. A loose battery sliding around a small boat is a hazard. See Marine Battery Care.

With the battery disconnected and the lanyard off, the kit bolts the starter and its bracket to the powerhead. If the motor needs a charging coil, that usually means pulling the flywheel, which takes a flywheel puller and a holder and must be tightened back to the service manual's spec. Most owners stop here and hand the job to a dealer. If you do it yourself, follow the kit sheet exactly and use the fasteners it supplies.

Follow the kit's wiring diagram exactly. Keep cables away from the flywheel, linkages and hot exhaust parts. Secure them so tilting and steering cannot pinch or chafe them. Yamaha points out that battery connections must be clean and tight, using hex nuts and lock washers, not wing nuts. Loose connections cause no-start problems and heat.

Before reconnecting the battery, have a helper confirm:

• The starter pinion clears the flywheel when at rest.
• No wire can touch the flywheel or move with the throttle.
• The shift lever moves freely through forward, neutral and reverse.

Reconnect the battery positive first, then negative.

With the motor in the water or on external flush muffs (never dry), and the prop area clear of people, try to start it in forward and in reverse. It must not crank. Then try in neutral; it should crank and start. If it cranks in gear, stop and fix it before using the boat.

The opposite problem is common too: nothing happens in neutral. Before blaming the starter, make sure the shifter is fully in neutral. A neutral switch that is out of adjustment, or a stiff remote control box that never quite reaches neutral, blocks the starter on purpose. Have the dealer adjust it; never bypass it. BoatUS's no-crank checklist covers the other usual suspects in order: the battery switch on, the kill switch clip in place, battery cables clean and tight, at least 12 volts at the battery, the engine's main fuse, and the main harness plug between boat and motor.

With the motor running at a fast idle, measure battery voltage at the terminals with a multimeter. It should rise above the resting reading. If it does not change, the charging coil, rectifier or wiring is not working. See Charging System Test.

Most small electric-start outboards keep a recoil starter or emergency rope as a backup. Make sure yours still works. If the battery dies on the water, that rope gets you home.

After the first few hours, look over the starter bolts, cable ends and the transom clamp screws or bolts. Yamaha suggests checking clamp screws and transom bolts after the first few hours of running anyway. Retighten anything loose.