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The GM Fuel Pump

Discussion in 'Gearheads' started by TwoForFlinching, Nov 21, 2020.

  1. TwoForFlinching

    TwoForFlinching Sharpshooter

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    My fuel gauge has gone all wonky. Everything points to the sending unit, everyone recommends replacing the whole enchilada. You ever done it? There's a debate raging whether to scoot the bed back vs dropping the tank vs paying the mechanic. Can you share your wisdom?
     
  2. Shinneryfarmer

    Shinneryfarmer Sharpshooter

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    First question. 1. How full is the tank? If it is below 1/4 drop the tank. 2. If it is closer to full either siphon it out or pull the bed. If you pull the bed access is easy but you will need 4 guys to lift it off or rig up a lift to pick up to allow access. 3 Have you checked ground wire at tank? If you have a bad ground wire where it connects at tank it will cause it to act goofy. Sometimes these get dirty or corroded. Also I have found a partially pinched wire or chewed wire by a mouse that will cause it to act that way. You can use a mirror and light to sometimes look for this issue. You didn't specify year so some years have a pig tail connecting wiring to tank these can also cause bad connections.
     
  3. Profreedomokie

    Profreedomokie Sharpshooter

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    A friend and I moved the bed on a friend's Chevy PU and changed the pump. It wasn't easy with just two of us.
     
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  4. dlbleak

    dlbleak Super Moderator Staff Member

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    What year? Different gens had different issues. 89-98 had fuel pump issues(and others). 99-06 had ground issues. 07-current have cluster issues.
    My 06 has ground issues that I’ve been chasing for years with no luck.
    Took the dash off of a guys 15. When they put the cover on at the factory, the main ground wire got pinched. It’s in the very corner of the dash on the drivers side.
    How old is your battery? Check it with a load tester.
     
  5. tRidiot

    tRidiot Sharpshooter

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    99-06 also has gauge stepper motor issues. I've replaced multiple and my oil pressure one is screwy and the fuel one is off by about 1/8.
     
  6. dlbleak

    dlbleak Super Moderator Staff Member

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    The oil pressure switch can be a PITA. Take the hood off and it’s much easier.
     
  7. Dumpstick

    Dumpstick Sharpshooter

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    Don't have to remove the bed completely. Just unplug/unblot everything, and tilt it up on the side you need to access.

    A jack, and some cribbing material, no problem.
     
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  8. TwoForFlinching

    TwoForFlinching Sharpshooter

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    It's an '05 1500HD Classic. Already replaced my gauge cluster. I've been counting miles on it the last few weeks, it's not super wonky yet, but will sway within 1/4 tank as you go down the road. I admit, I've never pulled a tank. My friend tells me I need a bunch of specialty tools to do it, but I think his experience was from a mid-90's S-10. 160k miles, I'm definitely due a fuel pump anyway.

    I was going to rig up a big H-brace under my bedrails and pick it with an engine hoist, just enough like dumpstick mentioned... eventually. I'll climb under there and test ground one of these days. As little as it fluctuates, I'm hesitant that's the issue, but due diligence and such.
     
  9. swampratt

    swampratt Sharpshooter

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    Check for recalls on the truck or the dash modules.
    I think 03 had a recall.
    This might help.
    https://my.chevrolet.com/recalls

    Beds are not that heavy just place a 2x6 under the bed and jack it up at one of the corners with a floor jack with a 4x4 placed on it.

    Once it is up wedge some boards under the bet between the bed and frame and crawl under it to pull the sender.

    If it is just fluctuating I would not worry about it.
    But I drive really old cars and see the fluctuations all the time.
    Carry a fuel can with you so when it goes empty you can fill it up on the spot.

    Now i like to take a new to me vehicle and drive it until it runs out of fuel just so i know what the fuel gauge will read or will act like when it is empty.

    I have had some read 1/4 tank of fuel and be out of gas.

    My 57 chevy is backwards because I stuck a Ford fuel gauge into it.
    Reads full when it is empty. Reads 1/2 a tank when it is full.
    That should screw up anyone that steals it.
     
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  10. Slim Deal

    Slim Deal Sharpshooter

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    I have replaced 3 on my Tahoe. It sucks no matter how you do it. Always had to lower the tank and it sucks no matter how you do it. Always check that the ground wire was no the problem and it sucks no matter how you do it. Yes it really does suck no matter how you do it.
     
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