Help! Electrical Fire

[C.O.L.]

So after using my boat multiple times a week since the start of boating season, I was out fishing and noticed an electrical fire under the hood of the engine. Two wires rubbed and burned. One Green, one Black. The green wire is melted right to the black one. They go into a plug that I have pictures of. I pulled the wires out and traced them all the way to the transom mount where they go in and Im not sure where they go from there. The harness is melted all the way to that point, and I couldnt cut open anymore. I don't know what to do from here and would really really like to know what these wires are for. I bumped the ignition key and the motor fired right up with those wires unplugged and melted. ANything at this point may help. Motor is a 1994 Johnson 70HP VRO.

This is the burnt side of the wiring harness. The striped/burnt wire is the green one which burned to the black one. Green one is not part of the plug.

This is the motor side of the plug, unburnt

another picture of the plug. The plugs home is behind the fuel filter

 

[toddschubert]

Re: Help! Electrical Fire

trim tilt working? (if it has one)

 

[C.O.L.]

Re: Help! Electrical Fire

Tilt trim works with all this unhooked. Not that

 

[C.O.L.]

Re: Help! Electrical Fire

Any ideas? Im kind of nervous to start it back up just to try and see what doesnt work

 

[daselbee]

Re: Help! Electrical Fire

Trim and tilt sender wires. For your gauge up front. I would look for the cause up front at the helm....even if you don't have the gauge. Harness problems up front, I think.

 

[C.O.L.]

Re: Help! Electrical Fire

Ok. I will check that too. I showed these pictures to my local marine mechanic at the boat dealership/service center and he thought that the wires may be for the Tachometer? Would that make sense? He said he knew for sure it was a wire that most likely ran to the console...But I already knew that. Do you think a bad voltage regulator could have caused this? Do you guys think it would be safe for me to leave the burnt wires unplugged and try things out while it is running to try and pinpoint what does not work?

 

[C.O.L.]

Re: Help! Electrical Fire

To help some more, I tested all of my tilt/trim up down switches (I have three) and all of them work. Im thinking because the wires continued to burn even after the engine was off and didnt stop until I cut power to the motor one of the wires is a constant lead that has power when the engine and ignition is OFF. So what all has constant power. And these wires are a part of the cluster that comes out of the bottom of the engine housing and goes into the motor mount plate, not from the cluster that comes out just under the hood seal that runs into the body of the boat with the steering and throttle cables.

 

[daselbee]

Re: Help! Electrical Fire

No power on those wires normally. They provide a variable resistance to the gauge to ground. As the motor moves up or down, the trim sender lever moves, causing the gauge to move. I repeat, there is no power (I mean real power, enough to burn wires). Any short to real power can certainly come from the gauge. In other words, look for the power lead at the gauge to be accidentally touching the sender lead. Something like that. Green and black are ground, the white? I think is the sender lead. Under the tilt mechanism, where the TT motor is, there are two big wires...green and blue. Now those wires have enough power capacity to burn your green, blk, etc. But only when the TT is engaged are they energized with +12v. So, You state they continued to burn until you cut juice....Look for an external short to +12v to any of those burned wires. Get a manual.