86' Shadow Bass Boat wiring help!

Ok, this is probably a shot in the dark, but I figured I'd try.
I just picked up an 86 Shadow Bass boat. The wiring is so messed up it is unbelievable. There are wires all over the place. The guy before me jerry rigged everything so bad that I can't tell any of the wires apart. I've been in the garage with a test light and a connectivity meter for the past 5 hours trying to make some sense out of it. So far I have the lights working and a couple gauges. My RPM gauge comes on when I turn the key but that is the only gauge that comes on. When I ground the fuel gauge it stays on no matter what position the key is in. When I try to plug the fuel gauge wire into the sending unit on the tank, the wire starts to smoke. The bilge pump wires are also messed up. I can get the pump to kick on but i cant get it to work with the automatic switch.
Basically my question is: Does anyone know of a place that I can get a wiring diagram for this boat? Or maybe a boat very similar to it? If anyone has owned a Shadow any advice or insight would help a lot.
Thanks

Re: 86' Shadow Bass Boat wiring help!

Welcome to iboats!

Your odds of getting the exact wiring diagram is pretty small, but, fortunately, boat wiring tends to be pretty generic. Take a lot at the stickies at the top of this forum section for starters.

Re: 86' Shadow Bass Boat wiring help!

Here is how the fuel gauge is wired:



Here is how all of the instruments are wired:



If the tach works but other instruments don't, it is very likely the +12 volt and ground daisy chain connections between gauges is interrupted somewhere along the line. Gauges are powered by the "A" (accessory terminal) on the ignition switch.

The bilge pump requires a separate float switch or a pump that has a built in float switch to work automatically. For all you know the pump may have been replaced with strictly a manual variety. If the pump has three wires it will be an auto type. Two wires it is not.

The secret to electrical troubleshooting is to focus on one area at a time.
1) verify power to the ignition switch ("B" terminal).
2) Verify power on the "A" terminal with the key on.
3) Verify power to the +12 volt terminal on ALL gauges.
4) Verify ground on the GND terminal on ALL gauges.
5) The fuel gauge, tach, temp, and trim gauges all have senders. Verify that the senders are ok. Tachometers use the send line from the regulator for "sense" (no separate sender).
6) There should be a black and red #8 or #10 pair of wires running from the battery through a fuse or breaker to the console to power accessories. That circuit typically feeds a fuse panel to which other accessories are connected.
7) The only accessories that should be powered from the "A" terminal on the ignitiion switch are the gauges.

IMPORTANT: Wire colors in the above diagram are not industry standard. They were chosen simply for visibility to distinguish the various circuits.