The Dodge Challenger Message Board

hello all,
I have been trying to sort out issues with my gauges and at a lost what to do. Both my fuel and temp gauge were dead. I traced the problem to the voltage limiter, and replaced it with a solid state one, now I have constant 5 volts. My replacement temp gauge is now working, but the new fuel gauge is pegged at full. I pulled the wire off the sender by no change, I then disconnected the sender, (purple) lead from the gauge and nothing happened. I then grounded the purple terminal to the frame and still it reads full. I don't know what else other than a bad gauge it can be. Any Ideas? The gauge came used off E-bay.

If the gauge needle jumps straight to full when the sender wire is put to a ground then the gauge should be good. The sender just provides more or less ground resistance as it moves up & down so when the tank is full & the sender float is pushed to the top of the tank it gives a 'total ground'.

So, if the gauge moved up quite smartly when it's got a good ground then you could assume it's working fine.
If it's reading full even when no power is put to it then it's screwed .
That leaves a problem elsewhere, so check the sender isn't stuck, check the wire from the sender back to the gauge thoroughly, could be a trapped or frayed wire somewhere?

Be warned though, if you ground out the gauge for long you'll fry it.

If you disconnect all wires from the gauge except the power source (voltage regulator), it shouldn't react (or barely move a little bit off from the bottom) when you turn the key to 'On'.
If it does, it's shorted internally.
It may be just a wire touching the frame inside the gauge, it's a simple galvanometer.
I'm not sure it's serviceable though.

Is the grounding strap on the tank for the sender?

Stupid me!
One of the mounting posts on the gauge was touching the dash housing. I insulated the cut outs and remounted the gauge. That brought the gauge to 1/4 full. I removed the sender and moved it through its range, it reads full, half or almost empty. Too many dead spots so I ordered a replacement. Thanks for all the quick responses, slowly getting the electrical gremlins sorted out.

Glad you got it sorted!