Blown Main Fuse, Chasing A Ghost

[jhoffman]

I may have caught him last night but my confidence on the issue wont let me stop thinking about it till I know.

 

Heres what happend, a few weeks back I was working on something, didnt think about it and started the boat with the charger on and plugged in. I noticed smoke at the control and shut it back off. I knew I cooked something. So into the control and I found the burned wire. I cut out the bad section, soldered in a new section, heat shrinked, wrapped in tape and went on my way. Now, at the most random times the fuse is blowing. Back into the control at least three times since then, a final one last night where I tore that control to ground zero and covered everything, checked everything from the trim switch to the key.

 

It wont blow this fuse on muffs in the driveway. I even tested it at night to look for arching. Ive been into the motor as well, the trim solenoid shows no sign of a problem, no wires in there show an issue, the relays look ok.

 

My question I guess is could those relays or the solenoid be bad and only show a problem at WOT. Remember, this is a very random time when this fuse blows. Also, I can see at least one wire under the dash that runs back with the control other than the tach and that looks to be the wire for the livewell switch. Should I fuse the wire after it leaves the control before entering the tach? Could the tach be demanding more than 12v at some point causing this fuse to blow? The motor was just rebuilt and never had issue till I pulled that bone head move. Its definitely not wires at the motor, like I said, I covered everything and rebuilt that control from scratch last night, took me 4 hours so I may have it fixed, if not, I dont know where to go from here.

[jhoffman]

Well, it blew the fuse again, after running great the day before with no blown fuse. I think I am starting to see some sort of pattern here when im coming out of no wakes, makes me think this tach is WHACK!

[J Francho]

Disco the tach, and see what happens. Good luck!

[grizzly1654]

Seems like you still have a dead short somewhere. Have you tried to wiggle the wiring harness around while it is running on the muff? 

If possible do one wire at a time to isolate the problem.