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Fuel Gauge Wiring

Discussion in 'Early CJ5 and CJ6 Tech' started by 53Flattie, Jul 8, 2012.

  1. 53Flattie

    53Flattie Intigator

    Where does the power come from for the fuel gauge? I searched and found that 12V being applied directly to the fuel gauge will burn it up. With that in mind, where then do you get the power to the gauge? I know the sending unit is basically a resistor to change the current to the gauge.
     
  2. dave74

    dave74 Sponsor

    Last edited by a moderator: Feb 1, 2016
  3. 53Flattie

    53Flattie Intigator

    Thanks Dave!
     
  4. 53Flattie

    53Flattie Intigator

    Okay a I have a 2-post, so I need an external VR. Where do get one of those?
     
  5. Walt Couch

    Walt Couch sidehill Cordele, Ga. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    [​IMG]



    This should be what you have for your 66 jeep. If not then will need pic of your gauges.
     
  6. 53Flattie

    53Flattie Intigator

    I'm sorry - I should have been more clear - I have an aftermarket speedometer. Is that a VR built in? (fuel gauge on the left, in the second picture)

    [​IMG]

    [​IMG]
     
  7. Bob-The-CJ

    Bob-The-CJ Member

    My fuel gauge was not working so I just tried the above. My Jeep is a 63 but the gauges look just like shown and my wire colors match also. The second I switched the key on there was a flash of light from the gauge which I can only guess was the regulator. The gauges still do not work but after that flash I suspect they won't.

    It was a brand new gauge (with temp/fuel built in) so I am not sure where to go from here. I had also just installed a new fuel sending unit because I believed that was the root cause.

    Bottom line I am pretty sure the diagram above has the hot (double green) and negative (white wire from sending unit) backwards. My gauge was wired up the other way to begin with.



    On your gauge (OP) I believe the after market gauges have the regulators built in.
     
    Last edited: Nov 12, 2013
  8. Alan28

    Alan28 Well-Known Member 2022 Sponsor

    This is my main on only problem to solve now.
    My odometer + gauges is new, my 2nd sender unit is new. I have a 1st new sender unit a little bit broken, but still working.
    I have a 1971 CJ5.

    With my 1st sender, when I was putting on the electricity, the gauge was moving, working 5 sec then back to zero.

    With the new sender, no move at all. And it was made by a pro, he said to me : I don't understand.

    So now I plan to make tests out of the Jeep;

    1- test the gauge : I'll test with batteries 3, 5 volts, to see if it moves.

    2 - then I'll test the sender unit Nr 1, even if broken a little bit, I'll see waht happens.

    I take a note test after test.

    When I know that all is working, I'll make a direct alim with a small battery to test.

    I should find an independant gauge, I suppose it is an amperemeter. ohmmeter.

    I thing tha tI have a friend in electricity to help me. I want to understand where is the problem.
     
  9. Focker

    Focker That's a terrible idea...What time? Staff Member

    I just noticed while installing a new temp gauge in my speedometer the the A and S are in a different spot than what the strap will connect to. I double checked the temp gauge that I removed and it's the same as the NOS. Can I make my own jumper like shown in post #6? Maybe that's why my temp gauge hasn't been working?

    Mine.
    [​IMG]
     
    Last edited: Apr 7, 2015
  10. Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member


    Yup.

    H.
     
  11. Walt Couch

    Walt Couch sidehill Cordele, Ga. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    For Focker: Your fuel gauge is not centered properly (as seen in the photo). The studs cannot touch the case. The cardboard backing on the fuel gauge needs to be oriented the same relationship to the case as is the temp gauge. One the fuel gauge is oriented properly then the metal strap will fit as designed.
     
  12. Focker

    Focker That's a terrible idea...What time? Staff Member

    Thanks for the replies.

    I probably should have described the issue better. The strap fits just fine, it's only pictured to show which strap I have. The fuel gauge was installed quickly for the photo.

    The posts on the temp gauge (both the old one and the NOS) are reversed. If you look closely you can see the stamped letters in the cardboard backing (NOS pictured). I've looked at other images online and I don't see any with a modified strap. I don't understand what I have going on? The fuel gauge works as it should but the temp gauge hasn't. I'm afraid to make my own strap and burn up the gauges.
    [​IMG]

    Here's what I want to do. I checked the ohms as posted here ohm test with the DVM and it's spot on. Maybe post reversal doesn't matter because there's only one ohm test for the temp gauge?
    [​IMG]

    The front of my speedometer.
    [​IMG]

    [​IMG]
     
    Last edited: Apr 8, 2015
  13. Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    It really shouldn't make any difference which post on the temp meter gets hooked up to the regulator post on the fuel gauge.

    H.
     
  14. Focker

    Focker That's a terrible idea...What time? Staff Member

    I went with the extended wire setup...Everything works!

    Thanks
     
  15. Walt Couch

    Walt Couch sidehill Cordele, Ga. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    I just looked at 4 of my temp gauges and the cardboard is marked the same as yours and they were all connected with the original strap. I think Howard is correct although I have never hooked one up with the jumper wire like you did. If it is working then good enough. Learned something new.:)