Thread: Fuel gauge problems

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Working on a hot rod 72 Jeep with the all in one speedometer fuel and temp gauge. It has a new sending unit but the old tank from the po wasn’t hooked up. So this never worked as far as I know since the temp tank. We have 12 v to top right terminal as you look from behind, sending unit wire on top left, flat gnd from temp gauge to fuel, ran volts down the sending unit wire and had 9v at end of wire. Also we tried a separate gnd to the gnd on both sending unit and gauge separately of course and putting 12v to the s/u terminal the gauge goes to full. We’re at a loss at this point.

Please forgive the ignorance but I can basically test a two terminal battery. Putting the digital tester on the sending unit terminals produces nothing in any combination. Frame gnd to pos, neg, between terminals etc. also check the gauge again and should there be 12.55 v on the top right and bottom terminals, the gnd has 12vs ??? Still nothing on the top left in any combination. Also I don’t remember where the amp light wire was but that’s off now.

I had the wires reversed. Hooked them up like in the diagram and turned the key and wala!!! Works, gauge went to near full which the tank should be. “SO THEN” I went to hook up the amps light and gauge went to E, took wire off and still no movement!! But I think I’m getting closer!!

Think I found the problem!! It was a bad lead from the ignition switch but in deciphering that I now broke a gnd or something, Jeep won’t start and has no power.

You popped a fuse

Nope, the melted connector to the batt terminal wasn’t making a connection to the actual terminal just power at the wire, same thing that happened to me when I installed an hei distributor the wire fell off the terminal but was still in the housing. I’m soldering and shrink wrapping the heck out of everything now so once I hav a solid electrical system maybe things will work then. Thanks for the help

Nope, back to no fuel gauge, but a lot of other things that didn’t work now do

Well that's progress anyway.

True very true!! Lol