electrical problem

I'm having an electrical problem.

Description of the boat: 1975 Starcraft Capri 20' fiberglass I/O 888 mercruiser pretty much all original.

To start at the beginning: 2 years ago everything except the trim guage, the volt guage and the horn worked fine. The trim guage is intermittently working. last year pretty much the same except fuel guage is off. This year prepped it to go out and everything is reading incorrectly. Tach is off by about 2 grand. Figured it was a ground problem so I ran a new ground from the engine block all the way to the back of the guages. The only thing that was fixed by that was the horn. Unplugged every connector on the thing and reconnected but it didn't help. with key on pulled and twisted on the wires everywhere with no luck. Running in the water volt guage makes it to 13 volts after throttle is opened up. It starts fine batt is fully charged. Also the speedo only shows I'm hitting about 27 MPH which is way slower than the 40 MPH I ran last year. Has anyone had this problem before? Where should I look next?

Re: electrical problem

speedo probably has clogged hose, or leak in the hose.

Re: electrical problem

Sounds like corrosion at the connections. The only way to deal with it is to disconnect the battery temporarily. Then disconnect each connection at the dash and at the various connection points on the engine. Clean each connection with brass wool and a wire brush until all is shiny clean. Then reconnect each, putting some anti-corrosion paste on each. Do one at a time so you don't mix up connections. Good luck and safe boating. Hy

Re: electrical problem

Connections look like new at the terminals along with the rear of guage cluster. Will clean and lube connectors this week and hope it fixes it.

Re: electrical problem

1975? All original? Hmm Sounds to me like corrosion is the issue. You may be able to clean some connections and bring things back to life. However the wires themselves, as well as the gauge internals, could be reaching there end.
Corrosion is rust and once it takes hold it's like a cancer, it can get into everything. You may be due for a re-wire and some new gauges if want things to humm again. But 33 years aint to shabby a time for things to last.