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Fuel Gauge Stuck on FULL.

Discussion in 'The Garage' started by The Butcher, Feb 7, 2006.

  1. The Butcher

    The Butcher 1/2 ton status Premium Member

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    The fuel gauge on my '90 K5 is stuck on full. Actually, past full in the 3 o'clock position. It has always gone past full when I fill it up, and it would swing noticeably back and forth as the fuel sloshed around during driving. Not a big deal since it still worked to show me how much fuel was left in the tank once the gas stopped moving around.

    For some reason after my last fill up and some subsequent driving it has stuck at the 3 o'clock position past full. Anyone know why this would be? I assume the float is probably stuck or something, but not sure how to fix it. Any suggestions would be appreciated. Thanks.
     
  2. readymix

    readymix 3/4 ton status

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    You have an open in the circuit somewhere. Check all the connections and trace the wires.
     
  3. K30Blazer

    K30Blazer 1/2 ton status Premium Member

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    or a magic truck. Think of the possiblities!
     
  4. sandawgk5

    sandawgk5 3/4 ton status

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    Yep full= 0 ohms of resistance. If you have no power through the circuit the gauge will fail full or higher as full on the gauge is a little more than 0 ohms.

    Ira
     
  5. readymix

    readymix 3/4 ton status

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    I though full was 90 Ohms...

    Then again I don't really remember as I changed mine a long time ago. It would make sense though as an open would be infinate Ohms. A short would be 0 Ohms.

    I do know for a fact that an open pegs the gauge past full
     
  6. The Butcher

    The Butcher 1/2 ton status Premium Member

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    Check the wires coming out of the tank, or out of the back of the gauge? Or both? Thanks.
     
  7. The Butcher

    The Butcher 1/2 ton status Premium Member

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    Yeah, magic until it stalls on the side of the road for some mysterious reason.
     
  8. bear76

    bear76 1/2 ton status

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    I've never seen mine on "F". I always run out of money before the pump stops:doah:
     
  9. The Butcher

    The Butcher 1/2 ton status Premium Member

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    The pump usually shuts off before I get to full b/c the pumps around here seem to have a $75 limit on them. I guess the increased gas thefts have made the stations limit the max amount you can get at one time.
     
  10. SchnorrCS

    SchnorrCS 1/2 ton status

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    Not to hijack or anything, but I'm putting in a new fuel gauge (autometer) and was wondering if anyone knew which wire on the tank was the sending unit. Or should I replace the sending unit too?
    Thanks and sorry...
     
  11. blackblazer717

    blackblazer717 1/2 ton status

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    my guage did the same thing about 2 years ago, i found two problems,
    the first was that the fuse kept blowing for the guages and dash lights, that was just wonderful, and causing the guage to reed full.
    Second, down all the way back by the tank their was a bundle of wires tucked next to the dvrs rear frame, and one of them was for the sending unit.... sure enough it was chaffed through and touching the frame.... yuck and it was badly corroded.
    i say check the fuse and trace the wires, like previously stated.

    LUKE
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    There is a connector near the tank (single prong if carbed) that you can disconnect, pretty easy to test from that point either direction.

    Wire is usually pink for carbed applications, can't recall what mine is with the TBI pump.
     
  13. The Butcher

    The Butcher 1/2 ton status Premium Member

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    It's TBI, but I'll start near the tank like you suggested. Thanks!
     
  14. mouse

    mouse 1/2 ton status

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    On TBI truck the tan wire is for the pump, the red is for the sending unit. My original '77 sending unit wire was tan. When I converted to TBI the gauge and pump didn't work too good when hooked up in reverse....:doah:
     
  15. The Butcher

    The Butcher 1/2 ton status Premium Member

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    Thanks for the info. I'm going to try and find time this weekend to track down the problem.
     
  16. wetbackZO

    wetbackZO 1/2 ton status

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    you lost the ground connection...I had a fun time figuring this out on my 79!
     

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