Fuel problem C15 MBN

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by MSS, Sep 23, 2022.

  1. MSS

    MSS Light Load Member

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    Feb 16, 2008
    Hagerstown,MD
    0
    My right tank is pulling fuel so I only fuel left tank. I don't see a hose that connects the two of them. Fuel from my left tank somehow gets into my right tank and takes away from my usable fuel. Any help would be greatly appreciated. C15 mbn
     
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  3. xsetra

    xsetra Road Train Member

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    Aug 21, 2011
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    Your truck draws from the left tank and the fuel returns to the right tank. Does your truck shut down out of fuel with the left tank empty and the right tank full?
    Look at your tank vents and fuel return lines. Either could be plugged or collapsed to the point of preventing flow.
    Good luck.
     
  4. ProfessionalNoticer

    ProfessionalNoticer Road Train Member

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    Apr 25, 2021
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    Some have crossover valves that fail after a while. I'd just replace them with a standard T fitting and be done with it.
     
  5. lester

    lester Road Train Member

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    Jan 2, 2012
    NW, Iowa
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    What truck?
    Pete's draw and return from both tanks. There is like a Reed valve on the return that basically senses pressure and returns fuel to the appropriate tank. That can get crap in it and stick one way or another. Or most likely your tank vent is plugged and pressuring a tank so fuel doesn't return to it.
    Then so magic voodoo happens when you park and the tanks will even out, or if parked on a slope it will go to the low side. Surface tension or siphon or something.

    Pull your tank vents and see if you can blow air through them
     
  6. Metalicious

    Metalicious Medium Load Member

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    Sep 27, 2015
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    You have locking fuel caps? If you do take a look at each cap and see if one is missing. If one is, find a magnet and fish it out of your tank.
     
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