If I have a wiring error, I simply can’t find it…UPDATE: FIXED!

[billw]

Outlandish idea….Being an EE, you probably have switches lying around from Lord only knows what. You aren’t using some kind of application-specific switch with a diode buried in it, are you? One that off is open and on is closed in one direction flow only? I always warn my son that, when the human mind doesn’t know the answer to something, it starts making stuff up. Case in point.

Long live American manufacturing!

[nj-boatbuilder57]

Nope.

While I do have a ton of weird stuff, this is just a garden-variety SPST Carling toggle.

[garry-in-michigan]

I am totally frustrated. Having gone through 3 service manuals and several parts books I can only conclude the wiring , service and operation of the vacuum switch is only covered in service bulletins. These are not as religiously kept or as accessable as the parts books. . . 🙄

[fleetwin]

OK, so the vacuum switch and wiring was NOT in the circuit when you connected the two lead coming out from under the mag plate…I guess my next step would be to go ahead and connect that stuff, then connect the two stop switch leads at the engine before your wiring/harness set up…This will tell if your wiring is at fault, or the vacuum switch wiring is to blame….
Again, without seeing your wiring set up it is kind of difficult to guide you here, so I want to be sure we are on the same page…
Is the mercury switch set up still in play? This vacuum switch wiring set up was changed a few times over the years, the latest style being the simplest….Mixing the various parts/pieces/wiring could create a problem….

[garry-in-michigan]

The mercury switch is supposed to take the vacuum switch out of the circuit an higher speeds. In other words at slow throttle settings it provides an electrical ground. (Of course all insulating sleeves and washers must be in there proper place.) Some models have a second switch which completes the starter solenoid circuit at low speeds. Others use a Cherry switch actuated by the shift lever. . . 😉

[nj-boatbuilder57]

Update:

I’m not (yet) an AOMCI member, you guys don’t know me from Adam. So feel free to close ranks & laugh behind my back. It’s ok. Seriously!

The harness wires to the switch ohm’d out as I suspected: from wire to wire: infinity with the switch open, 0.2 ohms when closed, and neither lead had any communication with ground in either switch position.

So I reconnected the harness wires to the magneto plate’s kill wires, but left the vacuum switch out of the equation (minimizing variables). Both plug wires spark with the switch open, and both are dead with kill engaged. OK….getting somewhere.

So I wired the vacuum switch back in. Really don’t see how it can have an effect based on what it is & what it does, but ok. Guess what? Both plug wires spark with the switch open, and both are dead with kill engaged…..just like they’re supposed to!

I cannot duplicate the problem. Can’t.

So I’m sure it looks like the only variable in the equation would seem to be me. Frankenstein engine, non-OMC wiring, home-made harness, modern Deutsch connectors, etc. "Operator error"…."Nut behind the wheel". Or as they say in the IT industry, "I think it’s a ID-10T error". I hear ya. But I didn’t imagine the spark. Really, I didn’t. And I haven’t changed a thing. Just disassembled & reassembled. Twice.

If it works, it works…and I shouldn’t overthink this. But I saw the spark on the ‘top’ wire with the kill engaged. I really did. I’ll do some more tinkering tomorrow, but for now everything is exactly as it should be. I have no explanation.

I appreciate all of your replies, and I’m sorry there’s no "eureka moment".

[crosbyman]

welll… if it works we will never know 🙁

let’s hope the problem comes back 😆

Joining AOMCI has priviledges 🙂

[garry-in-michigan]

Don’t feel like the Lone Ranger . . . I’m sure we all have had problem outboards that didn’t respond to our hard work. I know I have had a few that acted up after a careful tune up. All you can do is try again. I remember distinctly one that finally purred like a kitten – leaving me wondering whatI did the fourth time that I failed to do on the other three attempts . . . 😆

[billw]

If you were an AOMCI member, then these guys would tear you up even more. Ask me how I know this.

I was thinking about it last night and had come to a conclusion in my mind that, if not a weird switch, then the vacuum switch must have been connected with the mag wire on the center, insulated terminal and the wire coming from the kill switch, grounded at the vacuum switch, not connected to the other mag wire. That would make it so that, when you hit the switch, one set of points would be grounded but the other would be isolated. (Maybe you still want to scrutinize the ring terminal on the end of the mag wire, for a solid, reliable electrical connection.) But whatever. Water under the bridge. I’m glad it works; and thanks, actually, for the brain exercise. The most fun on this site in months!

Long live American manufacturing!

[nj-boatbuilder57]

quote BillW:

If you were an AOMCI member, then these guys would tear you up even more. Ask me how I know this.

Stands to reason, I suppose! 😀 😀

Thanks again to everyone for listening…

[Author]

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