New gas tank, new sending unit. I quickly touched the back of the gauge with 12v and the needle moves fine. Sending unit ground new and grounded.

I tried grounding the sending unit lead and the needle did not move. Traced wiring back to harness all looks good.

Ok, so now I moved to the gauge cluster itself. I am only looking to make the gas gauge work so it is the only gauge hooked up factory. I am using custom gauges for everything else. All wiring is stock and not cut up.

I replaced the voltage limiter with a few others I have.. nothing.. So I am down to the 8-prong connector on the circuit board. I only seem to get power from one of the prongs. All others are dead. Is this the prong that feeds the board? Is this how it should be? I see other prongs going to the fuel gauge and temp gauge etc. These prongs are dead. Shouldn't it be live?

what kind of car?

Do all the other guages work?

Could be the limiter if they don't work as well.

Usually when you ground the sender wire the guage will rise if it is good.

Tom

12 volts to the gage uh, it only needs 5v. So supposing you've not hurt the gage connect a voltmeter (+) to one side of the gage posts and the other lead to a good ground. Do you have 5 volts? Connect the (+) to other other post to be sure. If you have 5 volts there make a jumper wire that will run from the gage to the sending unit at the tank. The gage should work, if it does then you have a wiring problem from the tank to the gage. If it doesn't work it is probably the gage. If you do not have five volts at the gage then its in the dash panel, you might try to locate a 5 volt source on the panel and jump it to the gage, hook it to one terminal and the jumper wire to the other, if the gage works then Ohm the (original wire) from the sending unit to gage to figure which terminal is the correct one for the input. Now hook five volts up to the other terminal, and you should have a working gage. Electrical problems are the absolute worst to mess with. - good luck

Michael take the sending unit lead wire off of the sending unit & connect this wire to the battery NEG post with a long jumper wire(with an alligator clip on each of the ends) turn ign key on & see if gas gauge needle goes to full & holler back please.

Ya know, just a few weeks ago I was messing around trying to get mine to work in a A-100 when all I did was drop the tank to service it. Everything checked fine and it should've worked. In a fit of frustration, I beat on the sending unit with a screwdriver handle a few times. Guess what? Go figure? If that doesn't work, you can try a BFH. Good Luck

Guys,
Thanks for all the responses. I got it to work!! I had everything apart (except tank and sending unit, thank god..) but I had the dash out. I tested current to one side of the gas gauge and then it was on the other as well.. Now the other side is the wire that feeds the prong that becomes the wire to the sending unit. I did not have power there.. so I tightened the barrel nut on the gas gauge and that made a better connection to the circuit board and hence gave me the .5V back to the sending unit and bingo, gas gauge worked.

I'm glad you didn't fry it when you put 12V to it.

The quick application of 12 volts won't hurt it as long as you don't let it peg and only do it for a few seconds. The gauges are a little more robust than that.

A better test is to apply the voltage to the appropriate pin on the circuit board while the gauge is in place, because there are a few places for a bad connection to occur between the pin and the gauge, namely the pin-to-circuitboard pressed connection and the little stamped-nut-to-circuit board interface. The 8-peg connectors that attach to the circuit board can become loose and continuity can be lost there and corrosion can cause a loss of connection at the little mounting nuts.

You can fix this by soldering the pins to the circuit board and cleaning the place where the nuts seat. Be careful to maintain proper pin alignment when you do it, as they can become slightly askew during the soldering process and then not slide back onto the wireing harness.

There's an article detailing this in the August issue of one of the Mopar magazines.

Is the ground strap attached between the fuel line and the sending unit?