Strange electrical problem

[rdeto]

I have a 1981 overniter with an outboard. All original and meticulously maintained and cared for. Before i start the motor my fuel gauge wiper and running lights work fine. The fuel gauge springs up and lights and wiper works. When i start the outboard, the fuel gauge barely moves off the empty line and the lights and wipers no longer work. When i leave the boat overnite, the fuel gauge works as do the running lights and wiper until i start up the outboard. I checked the 6 dashboard fuses and all seem to be fine. Is there another fuse block in the boat I should be checking or go in a different direction. Any help would be greatly appreciated.
Thanx

 

[DaleH]

I'd check for a loose ground. Loss of ground can cause a whole host of strange issues. The gauge should be powered by a lead from the harness, that powers the gauge when the ignition is on. The wipers and lights should be on a separate run from the common pole of the battery switch.

I'd say you have either a poor or loose ground or wires with corrosion building up in them ...

 

[rdeto]

Thanx,will check for ground. Is there a common ground pole on the main fuse block or under the dash gauges?