Fuel Gauge Issue

Discussion in 'Dyna Models' started by RickyBobby, Mar 18, 2010.

  1. RickyBobby

    RickyBobby Active Member

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    It used to be that when my fuel lamp lit up on my 06 Dyna, I could see that the gauge on the cap was into the reserve section. I would fuel up. I usually got about 4 gallons in it to top up. The past couple times I have noticed the lamp on and the gauge in the reserve section, but I can only get a shade more than 3 gallons in to top up. Something is happening to my sender. Is it just wearing out? Can I remove it and adjust it a bit? Would I need to replace it to be more accurate?
    Meanwhile, I know from setting my trip meter that at 125 miles I need to think about gas. Since that works well, I don't know if I should even bother, but if something has a function, I like it to work properly. :)
     
  2. Chopper

    Chopper Senior Member

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    Here are some test you can run on the sender.
    THEORY OF OPERATION
    With ignition switch ON, the fuel gauge is connected to +12
    volts. Current flows through the gauge and variable resistor in
    the fuel gauge sending unit to ground. The sending unit float
    controls the amount of resistance in the variable resistor.
    Inoperative gauges may be caused by three circumstances.
    ● Sender or fuel gauge not grounded.
    ● Malfunction in sender or fuel gauge.
    ● Broken or disconnected wire from ignition switch to fuel
    gauge.

    1. Remove gauge. Ground Y/W wire of fuel gauge sender
    located at bottom of gauge. Turn ignition switch ON.
    a. Fuel gauge must indicate FULL. If gauge indicated
    FULL, gauge is functioning correctly. Proceed to
    step 2.
    b. If gauge did not indicate FULL, proceed to step 3.
    2. Set MULTI-METER (Part No. HD-35500) to RXI scale to
    measure the resistance of the sending unit. Place one
    probe on Y/W and the other probe on a good ground.
    a. If fuel tank is full, the reading should be 27-40 ohms.
    An empty tank should have a 240-264 ohm resistance.
    A half full tank will be approximately 97-118
    ohms.
    b. If a very high resistance or infinity is indicated on the
    meter, the sender may be “open” or not grounded.
    Check that sender and fuel tank are grounded by
    placing one probe of Multi-Meter on sender flange
    and the other probe on crankcase. Meter must indicate
    one ohm or less. Replace sender if one ohm or
    less was present. If a higher resistance is present,
    check for poor connection on ground wire.
    3. Check voltage to O/W (+) and BK (-) wire of fuel gauge
    connector [117] if gauge did not indicate FULL.
    a. Correct reading is equivalent to battery voltage.
    b. If battery voltage is not present check for broken or
    disconnected wire. Replace gauge if wiring problem
    is not found.
     
  3. RickyBobby

    RickyBobby Active Member

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    Wow! Thanks Chopper. I'll break out my multi meter and see if I can duplicate the tests. Nice that you have provided at approx ohms I need to see at the different levels too. Much appreciated. :)
     
  4. tonyboy59

    tonyboy59 Member

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    Me Too! Ricky! Same issue on 06 fxdwgi 4k miles!