fuel guage problems

[pandamarie]

I just installed a new fuel tank sending unit in my 69 charger and now the gas guage will only read half a tank when full, anyone know a fix for this problem?? I did use a 10 guage wire and stainless clamps in place of the ground strap that went between the sending unit and metal fuel line. tried grounding the tank directly to the frame also, still only reads half, my 70 challenger is doing the same thing but I havent replaced the sending unit on it.

[67Vette427]

Before I put one in I always check it in the car. I run a wire from the sending unit to the gauge and then check the movement of the gauge while I  swing it from full to empty. There could be a problem with your gauge and even the volt limiter has caused errors before. Good Luck!

[Bullitt-]

    I would think that you could unplug the sending unit & ground that wire, if you still read less than a full tank you will know its not the sending unit, if so you will know it is.

[Mopar73340]

   Take the wire off the sending unit and hook the wire to a good ground, the guage should read FULL. If not your guage is probably the culprit if the others are working correctly.

[RusTy/SE]

  I have that same issue with my Coronet...everything works save for the gas gauge...even the fronts of the temp control buttons glow a light orange when the lights are on but the gas gauge hangs around 3/8 and i would like to avoid running out of gas in this car. Thing is wiring-wise my troubleshooting skills are non-existant 
  Could someone post a pic or dumb down the explanation for me? I did replace the engine harness in my 73 Challenger before i sold it but that was literally an unplug the old - plug in the new situation. Troubleshooting wiring turns me into Patrick 
   

[Bullitt-]

RUSTY, There is one wire that goes to the sending unit on the gas tank (other than ground strap). Unplug it, ground it & see what your gauge reads w/ignition on. If not reading full you have a gauge problem, possibly wiring, if it does read full problem is with the sending unit, either faulty resistor or mal-adjusted float.

[RusTy/SE]

Thanks bullit, i'll check it tomorrow afternoon and post the result

[MEK-Dangerfield]

It's pretty easy to check out a gas gauge guys. Disconnect the blue wire that goes to the sending unit, and ground it. As was mentioned, this should make the gauge read "full" when the key is turned to the "on" position. The first pic. is how it should be setup now. The second pic shows where I disconnected the blue wire and grounded in to the ground strap for the sending unit, with a clip lead. Let us know what you find out. 


  Mike

[RusTy/SE]

  Today i got the Coronet running by having to put a couple of gallons in the tank and still having to prime the carb as it ran out of gas while sitting in my driveway ...let me mention here that one of the at-least 15-year-old tires blew last week  - also while just sitting in the drive   No harm to anything but ya's can all continue working on your respective projects as Mr. Murphy seems to be staying at my place for the time being 
  Anyways once i got the R/T running, i drove to the corner station to fill up but the gas gauge become secondary as the gas tank re-sprung a leak. I say "re-sprung" because (i checked with both parties and) according to the original owner and confirmed by the shop that always worked on the Coronet, the tank had been patched to repair a leak at the front "years ago".
  One new gas tank and sending unit as soon as the budget allows...   Not quite the way i planned on to determine if the gauge or Sending Unit is bad but still, thanks for the help folks

I purchased the gas tank for my 73 Challenger from these folks. Friendly and quick service. This time both Gas Tank as well as Sending Unit (3/8" for the 440) 


http://www.gastanks.com/prodinfo.asp?number=CR-14

http://www.gastanks.com/prodinfo.asp?number=SUCR14-38

Btw pandamarie, didn't mean to hijack the thread but did you ever resolve your gauge reading issue??

Russ