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Technical Gas guage

Discussion in 'The Hokey Ass Message Board' started by Pat Thompson, Apr 1, 2017.

  1. Pat Thompson
    Joined: Apr 29, 2012
    Posts: 198

    Pat Thompson
    Member

    Ok, I need some help. My gas gauge is pegged out all the time above full. Dropped tank and checked wires. The ground is good and I have partial continuity on the gauge wire. Is this right or should the gauge wire have none until ran thru the sending unit????
     
  2. Petejoe
    Joined: Nov 27, 2002
    Posts: 10,515

    Petejoe
    ALLIANCE MEMBER
    from Zoar, Ohio

  3. Mr48chev
    Joined: Dec 28, 2007
    Posts: 27,238

    Mr48chev
    ALLIANCE MEMBER

    That link will work but a car is usually going to have a different ground than a sailboat will .

    Pat did you check the sending unit with an ohm meter to see if it has the right resistance and the resistance changes though the swing of the float arm?
    Is there a good ground connection from the body of the sender to the chassis or body? That is quite often the issue especially if you put a layer of rubber or other material between the tank and the frame and the straps.
     
  4. Pat Thompson
    Joined: Apr 29, 2012
    Posts: 198

    Pat Thompson
    Member

    It is grounded good. The gauge reads all the way over past full. Every now and then, more then than now, it will work. It worked fine for 19 years and then started this. I guess I will have to pull the sender and see if it is working with a meter. If the sender wire was grounding somewhere between the gauge and sender would this show the same reading? It is pegged above full and normally never goes that high.
     
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  5. Pat Thompson
    Joined: Apr 29, 2012
    Posts: 198

    Pat Thompson
    Member

    10 years not19.
     
  6. squirrel
    Joined: Sep 23, 2004
    Posts: 46,505

    squirrel
    Member

    what kind of car is it? for example, Ford gas gauges behave the opposite of GMs when the wire is shorted or open.
     
  7. Pat Thompson
    Joined: Apr 29, 2012
    Posts: 198

    Pat Thompson
    Member

    32 Ford VDO gauges. Am I correct that if I ground the sending unit wire at the sender, the gauge should go to empty?
     
  8. Pat Thompson
    Joined: Apr 29, 2012
    Posts: 198

    Pat Thompson
    Member

    If it does not move, either the gauge is bad or there is a break in the sender wire?
     
  9. squirrel
    Joined: Sep 23, 2004
    Posts: 46,505

    squirrel
    Member

    VDO is 10 ohms empty, 180 ohms full. So if you ground the sender wire, it might go past empty. Or damage the gauge?

    If the sender wire or sender is open circuit, it should read past full.

    Make sure the gauge ground is connected, and the sender is grounded.
     
  10. Pat Thompson
    Joined: Apr 29, 2012
    Posts: 198

    Pat Thompson
    Member

    I pulled the sending unit wire off the gauge and touched it to the grounding lug and gauge went to zero. Looks like it is time for a new sending unit....
     
  11. Pat Thompson
    Joined: Apr 29, 2012
    Posts: 198

    Pat Thompson
    Member

    When I removed the wire, it went right back to the full side pegged. Time to pull the tank again. Thank you guys for your input!!
     
    Last edited: Apr 1, 2017

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