Not my boat but my sons truck and it's got me stumped.
85 Chev 1/2 ton with a small block. Ran perfect when he parked it.
No start yesterday and we found the fuseable link was gone on the firewall. I had one of those marine style 30amp inlines so we threw that on there for grins and no problem. Truck fired right up.
He got as far as the gas station and noticed the radio had quit working. Shut the motor off at the station and no start. It had blown the 30amp fuse.
Plugged in another one and brought it home.
With a fuse in it the radio is dependent on the rpms. Let off the gas and the radio works. Give it gas and it stops. Shut the truck off and it'll blow the 30amp fuse.
I also noticed that when the radio quit the stock volt gauge would peg.
I disconnected the alternator from the truck at the main post and found that everything works perfect. No blowing fuses, radio is perfect and all is well.
On a whim I threw my digital voltmeter on the alternator main post (while it's still disconnected) with the truck running and found 34.3 volts coming off of it.
I thought to myself "self, the regulator must be gone on this alternator" so I slapped on a used one I had in the shop and tada, same exact thing.
Does anybody have any thoughts or ideas? I'm all ears.........thanks...john