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Fuel Gauge

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by WinnipegK5, Apr 8, 2003.

  1. WinnipegK5

    WinnipegK5 Registered Member

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    My fuel gauge reads all over the place no logic behind readings. I have the tank out tonight to install a new hitch so I figure nows the time to find the problem. Any tips on testing to see whether it is the sending unit, wiring problem or the gauge??

    Thanks
    Mike
    Winnipeg, MB
    "That's in Western Canada where we support the men and women of the US Military" /forums/images/graemlins/usaflag.gif
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Does it bounce around when moving (like its measuring fuel "slosh") or is the reading random even if the vehicle is just sitting?
     
  3. WinnipegK5

    WinnipegK5 Registered Member

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    I doesn't slosh around. But you might fill it up one time and it would read 1/2 then drive for a day and then it would read 3/4 .

    Mike
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Hmm, could be a few things. Gauge, wire to gauge, ground from sending unit to body/frame, or sending unit itself. I'm sure there is a test for the sending unit, but no clue what it is, probably measure resistance as the float travels from the full position to the empty position.
     
  5. alec78

    alec78 1/2 ton status

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    To test everything except the sending unit and unit ground:

    Take a 90 ohm resistor (from radio shack) and connect it to the lead that connects to the sending unit. Your gauge should read a steady full tank. Remove the resistor.

    Next take 2 90 ohm resistors in parallel (giving 45 ohm in the circuit) connected as before. Gauge should read 1/2 tank.

    Put lead straight to ground (0 ohms) gauge should read empty.

    With no restiance in the circuit (open circuit) it should peg well past full.

    If the gauge reads fine, then you either have a bad ground or the sending unit is shot.

    If I get the time I'll post a diagram.

    Hope this helps.
     

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