FD-12 Shocking Experience

[david-bartlett]

I am working on my cousins FD-12 doing some long needed maintenance. One of the issues he had was getting an occasional shock while running the motor. He runs it on an aluminum boat, and this motor has a "Gil’s" extension handle in place of the infamously uncomfortable white factory grip. The "Gil’s" grip is aluminum also.

The only things I could find which might cause it to happen would be worn ignition wires, or the stop switch grounding out to the bracket that it sits in. The switch was loose and could move around enough to touch the underside of the bracket, and I could see where the paint was worn off where it made contact.

I also just remembered, one condenser mounting screw was loose as well and the condenser was free to move around quite a bit under the flywheel.

Do you think one of these issues could cause a little tingle while running the motor?

[fleetwin]

Well, the stop switch theory is easy to test out….Simply disconnect the two stop switch leads from under the mag plate (be sure to tape off/isolate the engine end of the stop leads) and retest for shocks.
Your other ideas are surely a possibility as well. Using a coil tester probe is the only way to really check for high voltage coil or plug wire leaks. Loose connections or frayed primary leads could cause this also. I suppose a bad plug could create a problem as well….
The mag plate is not very well grounded on these engines, theoretically a great ground is not needed, the secondary voltage path is easily completed through the mag plate bushing/crankcase pilot boss. Nonetheless, it sure can’t hurt to add a ground lead to the mag plate to ensure a clean secondary voltage path.

[crosbyman]

try running the engine in total darkness to see if any high voltage is jumping out of it’s assigned path ( plug wires, plugs..whatever)

you can get zapped just rolling a kart at walmart by static electricity build up from rolling wheels …getting zapped means you are becoming a component in the circuitry to ground !

is the engine mounted on wood / non conductive boards sandwiched on the transom…? try running a test ground wire between the engine frame and the aluminum of the boat

you need to provide a return path to ground other than via you body !

Joining AOMCI has priviledges 🙂

[westwind]

I have a 1955 QD that gives me a good shock sometimes. I’m thinking it’s the ignition wires but haven’t replaced them yet.

[auldscott]

The first place I’d look is where the high voltage leads contact the motor, especially where they drag across screws or castings during speed changes. And a wire may look OK at first glance, but if the insulation has once broken down to allow a spark to go to ground, there will be a tiny hole burned through the insulation.

Also check everywhere that the wire is clamped or secured; I had a motor with intermittent spark failure that turned out to be a thinned portion of insulation under a clamp.

Don’t think the primary side carries enough voltage to cause a shock, but I’ve no idea what the primary voltages are.

[david-bartlett]

Thanks for the suggestions. Motor is apart right now, and test tank is full of snow, so won’t be running anytime soon. I plan on replacing the ignition wires while I have it apart, and have insulated the wiring to the stop switch, so hopefully my cousin won’t get hit again when we are all done.

[jeff-register]

David,
Had, have a 63 200 that was burning points gold hot & misfires, The reversing current was stopped by bonding the mag to the block….BUT check everything please,

[crosbyman]

I doubt the kill switch is the cause as it only links the two sets of points " ground condition" to…. each other’s point sets hence, nullifying the point’s break condition on the primaries…… thus preventing a collapse of the primary coil current (which in turn normally creates the magnetic field to induce into the secondary coils and produce the high voltage spike to the plugs.

the zap you get is because you are a lesser resistance return path to ground . Feed it an even lesser resistance path than your body with a piece of copper wire mesh (mag plate to engine block and…. engine block to the boat aluminum structure. Either wire should stop your body becoming a path to ground.

Of course finding the problem is an better solution 🙂

taking the kill switch out only…prevents the motor from shutting down …….unless choked

Joining AOMCI has priviledges 🙂

[mikeg]

I had similar experience with a 1956 Evinrude Big Twin 30hp on my Feathercraft.
After changing ignition, and new wires, I was getting a shock touching both the motor and
boat at the same time. I came to determine it was the spark plug boot where it was shorting the system.
Changed the 2 rubber boots , and the motor ran flawlessly.

[jeff-register]

That’s it,
H.V. is different, brand new learning curve. Did mucho neon signs 4 Rt 66 @ 10% after cost & had a ball. At the risk of repeating, check everything.
H. V. Ele is lazy & will fault easier to you. Isolated grnd sept the aluminum boat…..Hello, I’ll bite you, 😯

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