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Technical Erratic fuel gauge

Discussion in 'The Hokey Ass Message Board' started by NAES, Apr 24, 2019.

  1. NAES
    Joined: Dec 24, 2008
    Posts: 434

    NAES
    Member

    About 200 miles into a 400 mile round trip the fuel gauge in my '53 Chrysler started bouncing all over the place.

    Fuel gauge is an original unit that works fine. Sending unit is one of those dial a depth universal ones with a wiper style resistor. Wiring is Rebel. Gauge always read fuller than actual. Probably my lack of dialing it in perfectly.

    First intinct is bad unit or bad ground. Anything else I should be thinking about as I dive in?

    NAES

    Sent from my SM-N910V using The H.A.M.B. mobile app
     
  2. BJR
    Joined: Mar 11, 2005
    Posts: 5,729

    BJR
    Member

    Check the ground first. If there is less than 1/4 tank of gas it may bounce the float around in the tank as the gas sloshes around.
     
  3. The wiper resistor could also have a bad spot on the sending unit, causing the resistance to change dramatically over a very short distance. As the gas sloshes, a little wiper movement can turn into a big change on the gauge.

    I have a similar problem on my '85 F-350. When the rear tank gets to half full, the gauge suddenly drops past empty, by the time the level gets down to about 1/3 full, the gauge comes back just fine. Scared the crap out of me the first time it happened as you don't want to run a diesel out of fuel. Now I know to just pay attention to the trip mileage.
     
  4. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 5,354

    Bandit Billy
    ALLIANCE MEMBER

    I had an LT-1 glass menagerie that did the same thing. I just averaged the sweep on the dial and lived with it for 15 years. Funny, it was the only car I never ran out of gas in.
     
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  5. NAES
    Joined: Dec 24, 2008
    Posts: 434

    NAES
    Member

    Finally messed with the gauge this morning. One look at the ground and I found the culprit! Cleaned it up and all is well.

    As a stroke of luck, I was messing with the idle speed when I noticed a pool of fluid on my fuel pump. I assumed leaking antifreeze but a sniff check confirmed it was leaking. A new one is on the way from my local Allied Parts House. Fingers crossed that it was my engine running lean which caused my overheating issue on my drive to Vegas. (Cooling system has been exhaustively gone through multiple times).

    Thanks everyone for always having rock solid answers for me! NAES

    Sent from my SM-N910V using The H.A.M.B. mobile app
     
  6. NAES
    Joined: Dec 24, 2008
    Posts: 434

    NAES
    Member

    The crappy looking grounding screw!

    And the offending fuel pump. After I soaked up the puddle of fuel. 20190509_103340.jpeg 20190509_110747.jpeg

    Sent from my SM-N910V using The H.A.M.B. mobile app
     

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