Fuel Gauge Issues.

Hey everyone, I am doing a bit of trouble shooting on my fuel gauge and having some issues. Issue one, IT DOESNT WORK HAHA. Well I have a 1977 Marquis tri hull with an evinrude 85. The tank is an 18 gallon tank and has a new sending unit. I measured the tank and cut the sending unit arm to length like the instructions. I purchased a new gauge and cannot get it to read. It has a ground that goes to ground on my wiring block and also a ground that comes from the tank. A red wire to the sending unit that goes to the S terminal on the gauge. A wire that goes to the light hooked up to my headlight switch. And the power wire comes from the ignition switch that sends power to the gauge when the key is turned.... Any trouble shooting ideas? My "fluke" meter said I had about 10.4 volts at the sending unit.... Thanks!

Re: Fuel Gauge Issues.

If what you say is true, then the unit should work. But since it doesn't, something you said is not correct. Here is a diagram of what the basic fuel gauge wiring looks like. Disconnect the sender wire at the sender. Now measure the resistance rather than the voltage. If you have some idea of how much fuel is in the tank, you should show somewhere between 33 and 240 ohms of resistance. 1/2 full is about 109 ohms give or take a bit. You can do the math for less than or more than 1/2 tank. Next, measure the voltage at the +12 volt terminal on the gauge. +12 volts is obtained from the "A" (accessory) terminal on the ignition switch, or the +12V terminal on any other gauge. If that's ok, then verify that the ground point for the gauge and the sender are ok. The sender ground does not have to go all the way forward to the ground buss on the fuse panel. It can be connected to the negative terminal of the battery. Next verify that the ground buss on the fuse panel is grounded to the negative terminal of the battery. If not, it is obviously not a ground buss any longer.

Re: Fuel Gauge Issues.

Mine did the same thing, brand new gauge and Livorsi sender, it was the ground at the tank was bad, regrounded it and it was fine.

Re: Fuel Gauge Issues.

Sometimes those float arms can get flipped 180 from where they should be causing the gauge not to operate properly.

Re: Fuel Gauge Issues.

Thanks for the replies everyone. I figured out the issue... The sending unit wouldn't ground itself. The ground wire was attached to the top of the sending unit but when the nut on the top was tight it wouldn't transfer the good ground connection to the lower part of the sender. I put a few small metal shims in and tightened it up and all was well. Here is a picture of where the connection was bad.