Re: 1987 mer/cruiser 4.3 sea ray seville
I just had an electrical issue with my '69 Searay SRV190.
I lost everything up front...gauges, accessories, everything.
A large orange wire comes up from the battery (indirectly) and connects to the ammeter. The ammeter then feeds the fuse panel. It seems the wire leaving the ammeter had failed at the connector. It was hard and dark indicating a heat issue. The wiring is 20 years old so I'm not too concerned about the cause of this. If it lasts another 20 years, I can live with that. I cut the wire back an inch, replaced the connector and viola - everything worked again.
You'll need to poke around with a test light to narrow your problem down.