fuel sender wiring

[cromagman]

I installed a permanent Moeller fuel tank in my aluminum boat. After thinking that I had all the wiring done I looked a little closer at the wiring instructions and they stated that I should run a wire from the sender to earth common. I do have one wire running from the sender to the fuel gauge, and another going to the negative battery post. There is no path from the battery ground to the hull of the boat, in fact I installed a cigarette lighter / map light in the dash, taking it great pains insuring that it did not ground through to the hull. I thought that there wasn't supposed to be any current of any kind going through the hull. I'm sure that by connecting the top of the fuel sender plate would cause the hull to be in the electrical loop so to speak. I hope that I'm making sense. My guestion is, does running the fuel sender to the negative battery post accomplish the same as purpose as running another wire to the hull. Sorry to being so long winded, about this, and I hope someone out there can clear this up for me one way or another. Thank you

 

[Bob Landry]

Running the wire to a ground buss will work fine. The instructions are probably written like that because a lot of permenantly installed fuel tanks are on larger boats with AC & DC electrical system. In those cases, AC ground(not neutral) and DC ground are bonded together along with any metal thru-hull fittings and the hull if it's also metal to put everything metal at the same electrical potential. That's done for electrolysis prevention which isn't going to occur in a small tin boat that's trailered.

 

[cromagman]

That makes sense. Thanks for the quick response. I just painted the boat today, so the last thing I neede was to rewire.

 

[PSG-1]

It's always smart to run seperate ground wires for everything, instead of grounding to the hull of the boat. This reduces the potential for stray current somewhat, although, the engine connection to the boat is what makes the hull 12 volt negative to begin with.

If your boat is properly wired, when you unhook the engine negative cable from the battery, leaving everything else hooked up, you should be able to put a meter with the positive lead on the battery, and the negative on the bare metal of the boat, and it should read 0 volts.

 

[cromagman]

I have not tried that yet as I have'nt had the motor on. What I have done is check for continuity between the negative battery post and the hull, and there was none. The same results betwwen the negative bus terminal and the hull. Once I get the motor on I will check it your way. Thank you.