Fuel gage only works with starboard engine running

[kloobs2305]

I have a 1996 Mainship 31 Sedan Bridge. For some reason the fuel gage for both Port and Stbd tanks only works with the Starboard engine running. (I fish with one engine only most of the time.) I tried to trace the DC wiring diagram but it is so small in the owners manual I cannot read it. So I am wondering if this is deliberate, (not sure why it would be) or if anyone has run into something like this before. Failing that does anyone know how to get a decent wiring diagram? Mainship is shutdown until spring due to lack of orders so doesn't seem I can get any help there.

 

[Silvertip]

Re: Fuel gage only works with starboard engine running

All of the other instruments are engine specific so you would likely have two voltmeters, two tachs, two temp gauges, etc. You only need one fuel gauge. Instruments are powered by the "I" (ignition) terminal on the ignition switch. Since you have two engines -- you have two ignition switches. The fuel gauge was likely wired that way because -- well, you only have one of them. So to make it work with either or both engines running, you run another wire from the "I" terminal on any gauge for the PORT engine into a simple Radio Shack diode and connect the other end of the diode to the "I" terminal on the fuel gauge. You disconnect the existing wire from the starboard engine ignition switch and insert a diode just like you did for the port engine. Now either or both engines will power the gauge and the diode prevent interaction with either engines electrical system. The solution will cost you about three bucks and some wire.