90 Amp Fuse Problem

steinwmj

New Member
Jun 26, 2009
15
Simi Valley, CA
The 90 AMP fuse at the starter blew while out on the lake. Boat just shut down and there was no power to the instrument panel. Replaced the fuse, batteries reconnected and when the battery switch was turned on to one of the batteries, the fuse blew again (pop sound at starter). The batteries are 5 years old but test good on smartcraft and with a tester. Does anyone have an idea what is happening? Could the batteries be bad or weak when loaded, could it be the solenoid on starter? Any ideas or direction would be most appreciated.
 
You have a short. Need to get out the wiring diagram and start tracing. The good part is there are not a lot of things between that fuse and either another fuse or breaker.

Best regards,
Frank
 
+1
I use to have a 2004 260 Sundance with a 350 MAG MPI that the wiring harness for the alternator was set up incorrectly and after a period of time the insulation melted away and created a short which blew the 90 amp fuse at the starter – Merc actually sent out a recall notice but unfortunately for me it came too late.

I know you have a 6.2 but as they are both 2004’s might as well start with the alternator wiring harness

Good luck
 
Thank you for suggestions. I will be looking at the wiring diagrams and also looking at the battery switch. I am wondering if the problem might be there. When the battery switch is turned to the off position, I am still able to lower the drive - it never did this before. I always had to turn the battery switch to move the drive up and down.
 
The 90 AMP fuse at the starter blew while out on the lake. Boat just shut down and there was no power to the instrument panel. Replaced the fuse, batteries reconnected and when the battery switch was turned on to one of the batteries, the fuse blew again (pop sound at starter). The batteries are 5 years old but test good on smartcraft and with a tester. Does anyone have an idea what is happening? Could the batteries be bad or weak when loaded, could it be the solenoid on starter? Any ideas or direction would be most appreciated.

Try removing the wires from the starter post to isolate the starter from the battery & to verify whether your starter has an internal short circuit or not. You will have to temporarily bolt these wires together for this test and tape them up so that they do not accidentally short to ground. If the breaker holds and everything else is operational, then it looks like you have starter issues to contend with.

~Ken
 
I will look at that. The bout was running (out on the lake) and just shut down as if I flipped off the run switch. All power to boat was lost and the instrument panel froze. Already changed the 90amp fuse once. Just odd that no warning from smartcraft and boat just stopped running. Batteries are original ones but always show good on display. Kind of puzzeled.
 
Problem resolved. It was the orange wire from the 90amp fuse to the alternator. It rubbed against a bolt wearing down the insulation. I was surprised that only about 1/3 of the actual wire was left. Had to splice-in a marine grade (water proof) butt connector and wrap with conveluted tubing. Installed new fuse and all electronics back. Found out that there was a Mecury Marine Service Bulletin issued. Thanks to all who helped.
 

Forum statistics

Threads
112,942
Messages
1,422,701
Members
60,927
Latest member
Jaguar65
Back
Top