Weird wiring issue

[captdiver]

I bought a Sweetwater pontoon with a 40 hp OB. The man I bought it from said there was a problem with the fuel gauge and he thought it was a wiring problem. When I turn on the key, the gauge doesn't move. But when I turn on the NAV lights, the gauge moves to 1/2 then when I turn on the key, it jumps closer to full. How the heck do I correct this situation? I don't want to mess up any wiring, but I would like to fix this. Thanks.

 

[Mc Tool]

Sounds like an earthing issue . Check all the negative connections from each load ( vhf , bilge pump , gps , etc ) back to the negative terminal on battery .
Ideally all the negs off each load should go to a common point rather than just be attached to an existing neg wire , and then one main earth back to the battery .

 

[captdiver]

Sounds like an earthing issue . Check all the negative connections from each load ( vhf , bilge pump , gps , etc ) back to the negative terminal on battery .
Ideally all the negs off each load should go to a common point rather than just be attached to an existing neg wire , and then one main earth back to the battery .

Thanks, I'll check it out.

 

[04fxdwgi25]

Yup, you have a bad ground somewhere