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Lurker52's avatar
Lurker52
Explorer
Jun 09, 2020

Water in fuel light came on then off

Hi Everyone,

Coming home this weekend from Panama City Fl. we drove through serious rain the whole way. We even had to detour off I-10 due to flooding. It was rain from tropical storm Cristobal.

Everything was fine until about 20 miles from home when the (water in fuel) light came on. I carefully kept going as there was no sign of anything wrong. The RV ran fine. The speed was the same, no sputter or hesitation.

After about 5-10 minutes the light went out. We drove the rest of the way home without any problem. When we got home, I restarted the RV and no warning light came on. Yesterday I did the same and no warnings. I drained about ½ a cup of fuel from the Fuel /water separator and I did not see any obvious water in the fuel.

I did some reading on this form and others and this seems to have happened to many during HEAVY rain. The sensor some how gets wet and the light comes on.

I have a Cummins ISB 5.9 engine. If this has happened to anyone else, I would like to here your experience. Is there any thing I should be concerned about in the future? I could not find the sensor on the F/W separator. If anyone know where it is on my motor, I was thinking of using some dielectric grease on it to help prevent this from happening

As always, I appreciate the help and comments.
Phil
Class A
  • ppine's avatar
    ppine
    Explorer II
    Jun 09, 2020
    drain your fuel filter. Then add some diesel supplement designed to take out water.
  • Ivylog's avatar
    Ivylog
    Explorer III
    Jun 09, 2020
    The sensor is fairly sensitive to water (go figure) so when the area around it gets wet it can give you a false positive ... fairly normal.
  • Executive45's avatar
    Executive45
    Explorer III
    Jun 09, 2020
    It, most likely, was a false positive but I'd get a bottle of 9.1.1. and throw that in there to be sure. Cheap insurance....Dennis
  • ppine's avatar
    ppine
    Explorer II
    Jun 09, 2020
    What is the point of having monitoring systems if you are second guessing them and assuming "false positives"?
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Jun 09, 2020
    Most Diesels. unless I'm mistaken have a "Water seperator" it can be drained. Sounds like it is time to drain it.

    Since I do not drive a Big D. and I'm do not "know" your rig I suggest you speak with someone who is either expierenced or a Diesel mechanic who can

    A: tell you if you have such a device
    B: Show it to you
    C: show you how to drain it (it is easy to do defently a DIY project).

    Like at your next Lube-Oil-Filter
  • RichNewcome's avatar
    RichNewcome
    Explorer
    Jun 10, 2020
    Here is what it looks like on my ISB.


    Click For Full-Size Image.

    On a previous DP when I had a lot less experience, I had a similar situation. I had just refueled and was driving in heavy rain when the water in fuel alarm came on. Not knowing what to do, I called ahead to a Cummins service center. As I remember, I had to spend the night there for them to check it out in the morning. The tech found what he said was water in the settlement bowl. So he replaced the filter and checked it out. When he gave it back he told me that the light had still been on, so he put dielectric grease in the connector which fixed it. When I said maybe that was the problem all along, he said that there was water in the bowl and therefore not a warranty issue. So a couple hundred dollars later, I was on my way again. From then on I kept a little grease on the connector. On my new DP (shown) the connector seems to be a better design a less susceptible to moisture causing a false alarm.
  • Airstreamer67's avatar
    Airstreamer67
    Explorer
    Jun 15, 2020
    I've owned my RV diesel for 24 years now, and the one and only time the "water in fuel" light came on was after I refilled the tank during a heavy wind-and-rain event under a canopy. A few miles down road the warning light flashed on and off a few times, but I kept driving until the rain stopped and I was able to pull over. I drained the fuel filter bowl of a few ounces of fuel. I don't know how much water it might have had in it, but that light never came on again. So whatever water I picked up, it was not enough to cause me real problems.

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