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Re: 70 Challenger Gas Gauge Dilemma!
[Re: DJVCuda]
#3146340
05/23/23 09:13 AM
05/23/23 09:13 AM
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Joined: Apr 2021
Posts: 143
Canada
EW1BH27
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member
Joined: Apr 2021
Posts: 143
Canada
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Did you make sure the float doesn't have a pin hole in it. Doesn't take much gas in it to keep it at the bottom. Might try adding a ground wire. Picture from Moparts from ages ago. My video of the ground wire in action. https://www.youtube.com/watch?v=gV_HMJa5maY
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Re: 70 Challenger Gas Gauge Dilemma!
[Re: EW1BH27]
#3146341
05/23/23 09:18 AM
05/23/23 09:18 AM
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Joined: Aug 2003
Posts: 11,179
Atco NJ
DJVCuda
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I Live Here
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OP
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Atco NJ
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Thanks for the reply!
I checked the float out of the tank - moved the float up and down manually and watched the gauge only move up to 1/8th of a tank while it was plugged in and grounded.
Thats what stumped me - because I can ground the sending unit wire and it goes all the way to full - didnt let it because i didnt want to fry the gauge.
I can certainly try the ground wire trick to the float though!
Last edited by DJVCuda; 05/23/23 09:18 AM.
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Re: 70 Challenger Gas Gauge Dilemma!
[Re: TJP]
#3146550
05/24/23 09:52 AM
05/24/23 09:52 AM
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Joined: Apr 2021
Posts: 143
Canada
EW1BH27
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Joined: Apr 2021
Posts: 143
Canada
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PS: By the way I meant to write that's it's pretty cool your dad (original owner) still has the car. Hope it stays in your family. Oh yeah, if there's a poor ground at the pivot point that'll definitely increase the resistance. And just to stress, if you do add the wire make 100% it doesn't interfere with the arm's movement. That's why I made the green wire on mine longer than the pictured one.
Last edited by EW1BH27; 05/24/23 09:58 AM.
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Re: 70 Challenger Gas Gauge Dilemma!
[Re: EW1BH27]
#3146560
05/24/23 10:43 AM
05/24/23 10:43 AM
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Joined: Jan 2003
Posts: 10,713
North Dakota
6PakBee
I Live Here
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I Live Here
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Posts: 10,713
North Dakota
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I've used this for flexible grounds on low current applications. Copper Soldering Wick
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
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Re: 70 Challenger Gas Gauge Dilemma!
[Re: DJVCuda]
#3146677
05/24/23 08:17 PM
05/24/23 08:17 PM
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Joined: Aug 2003
Posts: 11,179
Atco NJ
DJVCuda
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I Live Here
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OP
I Live Here
Joined: Aug 2003
Posts: 11,179
Atco NJ
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Re: 70 Challenger Gas Gauge Dilemma!
[Re: DJVCuda]
#3146699
05/24/23 10:17 PM
05/24/23 10:17 PM
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Joined: Jan 2003
Posts: 15,347
Omaha Ne
TJP
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I Live Here
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Omaha Ne
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UPDATE!
Ok- Had a gauge and sending unit from a 70 satellite to check things out as a double check!
IE
Wired the satellite gauge up and it worked fine - out of the car but from the plug and ground at the tank.
Pulled the front seat to get to the back of the gauge and checked from there:
Had the sending unit in the car with jumper wires, to eliminate the wire from the gauge to the sending unit and it didnt work. Jumped in the satellite gauge ( after voltage reducer, before gauge ) and it worked.
Plugged the wires back and ran a jumper wire from the outlet of the gauge to sender and it didnt work.
This sounds to me that the gauge is dead. Even though I can make it move with 12v by grounding out the sending unit wire at the back of the car!
WHEW!
if you put 12V to the gauge there is a good chance it's fried. Your description of what you've done is a bit confusing IE: Double checked the OHM's from both gauges. - 10 empty, 70 full I believe on both did you mean sending units????Jumped in the satellite gauge ( after voltage reducer, before gauge ) and it worked. Gauge or sending unit ???Plugged the wires back and ran a jumper wire from the outlet of the gauge to sender and it didnt work. 
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Re: 70 Challenger Gas Gauge Dilemma!
[Re: TJP]
#3146819
05/25/23 04:26 PM
05/25/23 04:26 PM
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Joined: Aug 2003
Posts: 11,179
Atco NJ
DJVCuda
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OP
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Atco NJ
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haha... yes i posted after a long couple hours in the garage and it shows! if you put 12V to the gauge there is a good chance it's fried. - Just touched it to see if it would move -
Your description of what you've done is a bit confusing IE:
Double checked the OHM's from both gauges. - 10 empty, 70 full I believe on both did you mean sending units???? YES Meant sending units!
Jumped in the satellite gauge ( after voltage reducer, before gauge ) and it worked. Gauge or sending unit ??? Gauge and it worked
Plugged the wires back and ran a jumper wire from the outlet of the gauge to sender and it didnt work. confused - I tried to eliminate the gauge, then the wire to the sender by removing the 5v supply to the gauge first - with a new gauge ( satty) and jumped to the sending unit. - that worked. I then plugged the gause back in and removed the other side, the outlet of the gauge in the dash to eliminate the wire.
it didnt work.
THe gauge only goes up to 1/4 tank when its supposed to read full
Hope that helps!
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Re: 70 Challenger Gas Gauge Dilemma!
[Re: DJVCuda]
#3146852
05/25/23 10:23 PM
05/25/23 10:23 PM
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Joined: Jan 2003
Posts: 15,347
Omaha Ne
TJP
I Live Here
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I Live Here
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Omaha Ne
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the gauge is powered by the 5v Limiter. The limiter is actually fed 12V and the points inside the limiter flutteropen and closed on about a 40% duty cycle thereby limiting the output voltage to 5V. that 5V is fed to the gauges via the circuit panel. the sending unit signal is a variable resistor to ground. That variable resistance is what makes the gauge read. You likely have an intermittent ground issue with the sending unit that is making you chase your tail. BTDT you can try a 10, 23? and 70 ohm resistor between the sending unit connector and ground MAKE SURE YOUR GROUND IS CLEAN and that your jumpers are not intermittent ( been bit by that more than once). The gauge should read High, Mid range and Low with each resistor. Give the gauge time to react when connected as they are slow to respond. 
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Re: 70 Challenger Gas Gauge Dilemma!
[Re: TJP]
#3147017
05/27/23 05:51 AM
05/27/23 05:51 AM
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Joined: Dec 2014
Posts: 5,804
ohio
ruderunner
master
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master
Joined: Dec 2014
Posts: 5,804
ohio
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If the Sattelite gauge works correctly when connected to the car wiring, that much proves out.
I'm thinking cluster ground or dash ground. Does the temp gauge work correctly? Oil pressure?
Angry white pureblood male
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