AQ125, what is this wire?

[SantaCruzin6]

Heya folks!

Can anyone confirm what this wire is? My mechanic thinks it might be the external regulator for the coil, but it's not currently hooked up to anything. The wiring on this boat is a bit of a mess (the previous owner wired up some questionable items) and I've been working to clean it up. To my recollection, this was never connected to anything since I've owned it. It certainly hasn't been connected to anything since I sent the boat to the shop for the $6k overhaul

For what it's worth, we're chasing an electrical issue where we aren't getting the expected voltage from the coil. With the key on, it is reading 3v roughly, not the 6v it should. When trying to crank, it stays around 3v not the 12v it should. However, when I go to stop cranking I get a brief flash of 12v, which sometimes actually starts the engine.

 

[Scott Danforth]

that should be the alternator excite wire

regarding your starting issue. service the points.... file them, rough gap them, use a dwell meter to set dwell, then set timing.

 

[kenny nunez]

It looks like the current alternator is a Delco 1 wire self energizing. The original Paris Rhône alternator used the wire in question.
To help the engine to start add a wire from the + side of the coil to the outboard spade on the starter solenoid. This wire will provide 12 volts to the coil im cranking mode.