Water in Fuel

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Yoster, Feb 1, 2023.

  1. Yoster

    Yoster Bobtail Member

    May 16, 2011
    Fort Smith, Arkansas
    This is on a 2014 Prostar. For a while I had the issue of everytime it would rain the notification for water in fuel would pop up on my dash. It would go away shortly after the rain stopped so I figured it was just a sensor. But for good measure I went ahead and replaced both fuel caps.

    Now however, the notification is staying on, and after driving through rain and stopping for fuel, I notice condensated water drops under both fuel caps. Assuming it's not leaking through the caps since they're both new and the inlet doesn't look damaged, where else can I look to try to find the source of the leak? Thanks.
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  3. lester

    lester Road Train Member

    Jan 2, 2012
    NW, Iowa
    If you have water leaking in, which I doubt, you would have fuel leaking out. Do you see fuel leaking out?
    Oxbow and Yoster Thank this.
  4. kemosabi49

    kemosabi49 Trucker Forum STAFF Staff Member

    Jan 13, 2013
    SW Arkansas
    Might not have a leak. When the warm fuel in your tank from the fuel return cools off after shutting down the truck, condensation will occur. The fuller your tank is the less room for condensation.
  5. Yoster

    Yoster Bobtail Member

    May 16, 2011
    Fort Smith, Arkansas
    I don't see any fuel leaking out, but what's gets me is I feel like the only time I see the water under the fuel cap is after driving through rain. Fuel should be fine, I fuel at Love's and TA.
  6. xsetra

    xsetra Road Train Member

    Aug 21, 2011
    Just random thoughts. I don't have the same truck as you.
    Put the old fuel caps back on. See if the warning reverts to the way it was.
    Does your caps have seals? Change the seals.

    Where is the fuel/water sensor? In the fuel tank or by the filter?

    Could it be a short in the wire harness that gets wet when it rains?
    Oxbow Thanks this.
  7. ducnut

    ducnut Road Train Member

    Dec 31, 2010
    You might try this stuff:

    I drive a ‘20 T680. I had a dozen random codes stored and one was for water in the fuel. Tech said to not worry about it.
  8. jaffles

    jaffles Light Load Member

    Oct 18, 2017
    Can you drain the fuel filter? Is there a water sensor at the bottom of the fuel filter?

    I also use Fuel Doctor every fill, not only disperses water but cleans the fuel system and controls algal issues. I find FD with standard diesel is the same price as premium diesel but achieves more.
    ducnut Thanks this.
  9. AModelCat

    AModelCat Road Train Member

    Jul 7, 2015
    If the WIF light is on, crack the drain on the seperator open slightly. Drain some fuel into a clear container and see if there is actually water in there.

    If there is water, find out how its getting into the tank.

    If its just diesel, troubleshoot the WIF wiring/sensor. It could be getting triggered by water spray from the road getting into a plug or damaged spot in the wiring.
  10. runningman0661

    runningman0661 Road Train Member

    Mar 5, 2009
    Clover, South Carolina
    I get the same notification in heavy rain in my 2018 international, it goes away after a few minutes. I just ignore it, my fuel water separator filter doesn’t show any increase.
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