Messed up fuel gauge?

Discussion in 'Trucks and Trailers' started by TracStr400, May 2, 2000.

  1. TracStr400

    TracStr400 LawnSite Member
    Messages: 48

    I have an '87 3/4 ton 4x4 Chevy. 350 TBI. I have factory dual gas tanks. The gauge is always right when I use just the right side tank. When I switch from the right tank to the left tank the fuel gauge will give me a random level. Sometimes it keeps the fuel level of the first tank. Other times it will go way past full and point downwards. And sometimes it will just read half empty or empty. My point is the stupid thing doesn't give an accurate reading after switching from one tank to the other. And I have no idea how much gas I have left (not good). Any help would be greatly appreciated.
  2. GMC85MAN

    GMC85MAN LawnSite Member
    Messages: 6

    I have the same trouble with both of my trucks my 85 GMC and my 82 Chevy(both have saddle tanks). I've heard the same problems from many other people so it must be something with the gauge inside the tank. Yes it is aggrivating. I've run out of gas atleast twice in both trucks.
  3. yortengel

    yortengel LawnSite Member
    Messages: 216

    <p>I used to have the same problems. I replaced the switching valve. And that fixed it. On my truck I also had to replace the fuel gauge. But that was a different problem than you are having. Any way the fuel selector valve also has the fuel sender wiring in it. At least on the 80's vintage it’s like that, I am pretty sure its that way also on the FI models. It’s a motor that switches the valve. If it does not travel all the way then it gives you an open condition. (Fuel gauge will read way over full) Mine was just plain broken. You can diagnose this condition by unplugging the six-pin connector and using a jumper wire. Jump the sending unit wires and see how the gauge reads. You will have to get the book and see the colors of the wires. I don’t remember what they are. <br>Good Luck.<br>
  4. TracStr400

    TracStr400 LawnSite Member
    Messages: 48

    Thanks for the help guys. I'm sure you just saved me some big bucks!
  5. chevy4ever

    chevy4ever LawnSite Member
    Messages: 8

    You might also check the float. Sometimes they are turned wrong or they can become saturated. Also, before you go buy switching valve, try unplugging the wires and plugging them back in. <p>----------<br>A Cut Above<br>

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