Fuel Tank Gauge Unit Grounding

Electrical & Ignition

  1. wihaltom

    wihaltom Member

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    I know this has been discussed in some other threads but I can't find what I'm looking for in any of the threads.
    I am trying to get my fuel gauge to work.
    It registers between 3/4 and 1/4 from full to about 1/3 tank.
    I got under the car and looked at the sending unit.
    There is no ground wire for the sending unit.
    Only the wire to the gauge.
    How does the sending unit get its ground?
    Is there supposed to be a ground strap that bypasses the rubber fuel line connected from the sender to the fuel line?
    Is the tank itself supposed to be grounded to the frame or something else?
    I am thinking the problem is a ground problem but I don't see where the ground comes from.
    My GM and Ford cars all have a ground wire attached to the senders and grounds to the frame.
    Thanks for whatever help you can provide.

    Weldon.
     
  2. Newp

    Newp Active Member

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    That's the way it is on my '78 Newport, but when disconnected the gauge doesn't work at all. (stays on empty.)
     
    Last edited: Apr 5, 2013
  3. wihaltom

    wihaltom Member

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    I added a ground wire from the fuel line from the sender to the frame.
    Same result.
    The gauge does go to past Full when grounded.
    I'll keep chuggin' at it.
     
  4. bluefury361

    bluefury361 Old Man with a Hat

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    [​IMG]


    This is what you need. Most mopar suppliers will have them.
     
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  5. 1966newport

    1966newport Well-Known Member

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    sounds like a bad sending unit
     
  6. Zymurgy

    Zymurgy Old Man with a Hat FCBO Gold Member

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    X2 I think it is a bad sending unit too. I forgot to install the clip above on my new sending unit and it still worked perfectly. Sending units seem to loose their calibration over time or in some cases never right from the get go. I got a new one from auto zone I believe. This was debated with me over rebuild old buy new. I went with new form the good responds from other members. I couldn't be happier it is the most accurate sending unit I have. On the E line it has 5 gallons 1/4-10 gallons, 1/2-15 gallons.... It can be done in place it is a pretty easy job if it is on a lift, but I imagine the old one is stuck in there pretty good.
     
  7. bluefury361

    bluefury361 Old Man with a Hat

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    I am trying to get my fuel gauge to work.
    It registers between 3/4 and 1/4 from full to about 1/3 tank.

    If the gauge is regestering then it is getting a signal and a ground.
    Could very well be a float issue.
    You will have to remove the sender unit to check/service it. If the sender looks ok just change the float, otherwise change the unit. At the least you will need a new gasket to reinstall it.
     
  8. theos911

    theos911 Well-Known Member

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    If the sending unit is not grounded I am pretty sure you should be reading full empty.
     
  9. commando1

    commando1 Mr. Natural FCBO Gold Member

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    "Full empty."
    Lemme think about that...

    < Sent from my tablet >
     
  10. theos911

    theos911 Well-Known Member

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    Sorry, Dramamine was still working on my brain from a 22 hour bus ride back from performing in Disney.

    Correction: If the sending unit is not grounded I am pretty sure you should be reading completely empty
     
  11. wihaltom

    wihaltom Member

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    What is the range of ohmic values from full to empty?
    On my 64 El Camino, it is 0-30 ohms = empty to full.
    Same thing for the new sender in the 67 Cougar.
    The sending unit that is installed is a relatively new one.
    It was installed with a new tank in 2005.
    That being said, that doesn't mean it works correctly.
    Are there different senders with different ohm readings or are they all the same except for the line size ( 5/16 or 3/8 line)?
     
  12. theos911

    theos911 Well-Known Member

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  13. wihaltom

    wihaltom Member

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  14. theos911

    theos911 Well-Known Member

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    You're welcome. I'm going through the same stuff with 73 Fury atm.
     
  15. wihaltom

    wihaltom Member

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    I wonder why gas gauges give so much trouble.
    I have three old cars (and going this afternoon to look at a 65 Chevelle SS) and they all have or had a problem with the gas gauges.
    I think it may have to do with the reformulated gasolines we are forced to use now.
    Lots more corrosion in the fuel systems than before.
     
  16. theos911

    theos911 Well-Known Member

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    My sending unit is actually fine - and I replaced the instrument panel. All that really leaves is the line from the tank to the gauge.
     
  17. commando1

    commando1 Mr. Natural FCBO Gold Member

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    Because people are too damn cheap. Years ago I remember dropping tanks constantly. Now? Two things people never fix. Fuel guages and A/C. But they have to have the pimp wheels and da stereo.

    < Sent from my tablet >