Gas Gauge Question • The Dodge Challenger Message Board

by **roadrunner** » 15 Feb 2004 12:19

I put a new pod dash in my 70 Challenger. Then I noticed the gas gauge acting spooky. When you turn the key to ACC to run the radio and so on, should the gas gauge move up? They way it is now, is the gauge moves up a little then stops when you turn the key to ACC OR to start the engine. But it never gets much above the E mark and the tank is more or less full. Could I have wired it up wrong, tank sender problems, or perhaps a ground issue? One last note: After I installed the dash it did work for a short period. But the gauge moved to FULL when the key was moved to ACC OR to run. But I'm not sure it was suppose to do this. Any thoughts on this are welcome.

by **dave-r** » 15 Feb 2004 12:44

You will find solutions to electrical problems in the electrical section. Follow this link;

http://challenger.mpoli.fi/phpbb/viewto ... =6601#6601

I posted a series of tests there that might help you. Good luck.

by **roadrunner** » 16 Feb 2004 11:49

Dave or anyone,

If you turn the key to ACC. should the gauge just set in the "E" position or register what is in the tank?

by **dave-r** » 17 Feb 2004 8:23

I went to check and my gauge has stopped working!

by **Philthy** » 17 Feb 2004 15:21

Hope you don't need your old sender unit back, Dave!

by **dave-r** » 17 Feb 2004 21:03

It happens now and again. Maybe a couple of times a year. Sometimes it goes to zero while driving on a long run. I have panicked a couple of times when I have been 30 miles or more from the next gas station and have looked down to see that! :shock:

This does not help out though. Come on guys. Answer the question!

by **roadrunner** » 17 Feb 2004 22:19

For the fun of it, I turned the key to ACC on my 69 Road Runner and it stays at E. But I don't know if this applies to my Challenger. About 25 years ago I grounded the RR tank to the frame using a small wire. Maybe that's what I need to do the Challenger. Maybe it's lost it's ground?? But if it did lose it's ground would it cause the gauge to go UP when the key is turned to ACC???

by **71_DEPUTY** » 18 Feb 2004 0:07

EASIST WAY IS TO TAKE THE DARK BLUE WIRE OFF THE TANKS SENDING UNIT AND GROUND IT TO THE FRAME- A NICE AND CLEAN BARE METAL ONE!!!.

sorry about caps!

if the gauge goes to full, then all is well- time to check the sending unit- but make sure that the tank has a good GROUND!! VERY IMPORTANT!.

if there is no reading when you ground it- make sure that the voltage limiter is being supplied with 12 volts- check the fuse!!- if fuse is ok- then measure the output of the voltage limiter- should be pulsing from 4- 9 volts?? that's ok because the average voltage is about 5 volts for the gauges. if not- check the black wire for 12 volts- if not- then go to the fuse!!!!!!! usually the acc.fuse. if 12 volts in- and no 5 volts out- limiter is toast!!! note- limiter has to be grounded to work proberly.

If there is pulsing voltage- then check to see if the gauge is working- try this- on the left side of the drivers side is the kick panel- remove it and there should be a electrical connector for the rear wiring- find the dark blue wire- the same one that goes to the rear tank- ground it out to see if the gauge moves. if so- then there is a problem in the wiring from there to the tank. if not- make sure that the wire is one the back of the gauge.

P.S- make sure you have the ing.switch on when you check the above.

by **dave-r** » 18 Feb 2004 8:18

Exactly where is the voltage limiter? If it is in the dash my fault may be a bad earth in that part.

by **six pack** » 18 Feb 2004 23:50

Voltage limiters push into the back of the printed circuit board.
They have 3 prongs and are 1 1/2" 's long.

Hope this helps

There was an article way back telling you how to convert this to a modern electronic piece for constant voltage.

by **dave-r** » 19 Feb 2004 8:17

Printed circuit board? I don't remember seeing one. Is it at the back of the gauges or the switches? I have had both out a few times (built Sept/Oct 1969) and do not recall seeing this.

Then again my lack of memory is getting famous!

by **Philthy** » 19 Feb 2004 12:34

Roadrunner, FWIW I had exactly the same symptoms on my '73. I went throught the checking process from front to back (had the pulsing light on the wire check probe, etc), took the sender unit out of the tank, the cover off the rheostat on the unit and noticed the insulation was very crumbly. After a bit of bodging in this area I did get the fuel gauge working again but only for a short while. Dave R kindly sent me a spare sender unit which I installed and so far so good (touch wood) it measures throughout the range! Also, as said previously a good earth helps, too!
By the way, be careful when removing the sender unit - I was a bit heavy handed with mine and the brass float popped off the unit and promptly floated to the other side of the tank! Took me ages to fish it out again and I couldn't go near a naked flame for the rest of the evening!

by **six pack** » 19 Feb 2004 21:22

dave-r wrote:Printed circuit board? I don't remember seeing one. Is it at the back of the gauges or the switches? I have had both out a few times (built Sept/Oct 1969) and do not recall seeing this.

Then again my lack of memory is getting famous!

The printed circuit board is the back of the gauges,cluster, and is a road map of all the circuits. Wait a minute, I'm in the middle of resto with the Dart...
Here's a pic

All of the Brown is the printed circuit board. and you can see the limiter at the top center of it.

Cheers

by **moparmaniac (owner4)** » 20 Feb 2004 1:47

The Dusters did use a printeted style circuit board, but the E-bodies did not. Here is a pic of a ralleye guage set up. It relied on jumper wires to complete the circuit.

by **six pack** » 20 Feb 2004 4:22

Sorry got of topic with the PC board.

Voltage limiter is the same only it is held down with a screw and the leads to the gauges plug in the top side.

by **dave-r** » 20 Feb 2004 8:56

Ah! That is what I remember it looking like Moparmaniac. Just a bunch of wires and no circuit board. At least now I know what to look for. Thanks both of you.

by **roadrunner** » 20 Feb 2004 12:00

Philthy thanks for your tips!! With respect to the voltage limiter, is that the little square box on the back of the fuel gauge? I haven't really looked yet but if the sender is shot I suppose I will need to pull the fuel tank, right?

by **dave-r** » 20 Feb 2004 12:48

You don't have to remove the tank. There is a metal ring holding the sender in the side of the tank. A few taps anti-clockwise with a hammer and it is off. The sender then just lifts out.

by **71_DEPUTY** » 22 Feb 2004 18:25

it bolts to the backside of the dash- three wires come off it- 12 volts, 5 volts for the gauges and the centre?( if I remember) is ground- but is already grounded by the case.

by **Christer** » 12 Feb 2005 21:42

I thought I would pass on this article from MA (Aug 2000). It feels like it is quite good. My idea is that if I post it, then maybe Dave can explain what it is all about. :crazy:

Sometimes it feels like Dave is the only one on the MB who doesn´t think that electrons is something you can eat. :s005:

I am not much of an electrician myself. To read a circuit diagram feels quite straightforward, but to use it in practice, isn´t always very easy. :s006:

....but I try not to give up! Everyone can improve, even you and me.