13 Peterbilt 386 Fuel Gauge Not Reading

Discussion in 'Peterbilt Forum' started by chevjen, Jul 31, 2021.

  1. chevjen

    chevjen Bobtail Member

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    Jul 31, 2021
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    Hey everyone. Just picked up a 13 386 about a week ago and it ran out of gas just a few hours after leaving with it. The passenger side fuel tank was bone dry and the drivers side had about a 1/4 tank but the gauge in the truck was reading 1/2 tank. Took it to a dealership and they replaced the sending unit and said yup all good to go and yeah, no it is not. Filled up both tanks earlier and the passenger side again was a little more than a 1/4 tank but the drivers side was full to the top. Any suggestions on troubleshooting or what the issue might be, obviously no fuel is being drawn from the drivers side and the gauge is not reading levels properly. Thanks!!
     
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  3. lester

    lester Road Train Member

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    Jan 2, 2012
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    Well it depends a little on how it's setup but most likely I'd say one of your vents is plugged and it's returning all the fuel to one side.

    Also there is probably a switch on your dash to select left or right fuel tank for the gauge? Are you watching both tanks?

    And it's not uncommon for the sending units to read inaccurate. As in showing a quarter but being empty. Probably can be adjusted but it's kind of a pain to do if you can't easily pull the sendor out of the tank on the truck. Just get to know your truck and know that 1/4 means you are on fumes.

    And it's fuel, or diesel. Never gas
     
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  4. chevjen

    chevjen Bobtail Member

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    Jul 31, 2021
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    Thank you for the suggestions on what to check or look for and yes totally meant fuel as I mentioned it the rest of the way. It was a long day. Thank You.
     
  5. King Michael

    King Michael Light Load Member

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    Nov 20, 2018
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    What Lester said is exactly correct.

    A quick home (possible) fix...
    Remove the return line (runs from top if tank to "T" somewhere under truck. Return line is typically 4 to 6 feet long.)
    Cover one side with a rag or towel and blow compressed air thru other side.
    If any debris is in line, rag will "catch" it and you will be able to see it.
    Do this for both sides.
    Also carefully blow air, (remove fuel cap first), into vent on top of fuel tank.
    Lastly, remove feed lines, usually located near bottom of tank (should be a shut off valve near bottom of tank. Make sure you shut it off otherwise all your fuel will drain out)
    Remove feed line from "T" (some fuel will drain from line)
    Again, cover one side with a cloth or rag, and blow compressed air thru other side.
    Note... Blow air thru line the opposite way fuel travels.
    Blow air into side that connects to the "T" (also called a fuel block)
    Reconnect lines, open fuel shut off valve.
    There are other possible things that can cause this problem, but this is the most common issue.
    Hopefully you got a warranty with your truck.
    Skill level... Novice
    Time... 1 hour.
    Patience level... l high.
     
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