I have a 2008 F-250 lariat powerstroke 6.4L. I have seen quite a few threads on this item. My drain water seperator light keeps coming on after you drive about 7 miles. Every time. It's still coming on and here is what I have done to combat the problem.

-I have started running top quality diesel last couple tanks. Shell is the best I hear.
-I put diesel additive in every tank since (seafoam, and now Lucas)
-I changed the fuel filters out (Motorcraft part)
-I have drained the water seperator every other day, and primed the fuel filter by turning the ignition for 30 seconds a time....4 times or so.
-When I drain the seperator sometimes it has a tiny bit of water in it...sometimes it looks like good diesel.

The dang light is still coming on. What is the deal?

Is the water seperator a different tank or is that fuel in there coming from your active fuel filter?

 

It sounds like you have a faulty sensor. Check the 6.4 site, I recall seeing a thread about the same problem you're having. LEO.

 

If you are draining your separator every other day and sometimes seeing visible water, I'd say the system is working and you are getting water in your fuel somehow. I change my fuel filter about every 12 to 18 months. I have yet to get a water in fuel light and I have never seen water in the separator.

Just my $0.02.

 

well, let's see I drained a total of about 3 16oz bottles out. Two had water settled in the bottom and one was totally clean. I am thinking it is working properly, and maybe I am getting it out of the system gradually.

I am getting the drain water seperator light, but never had the water in fuel light.

 

If anyone's interested, I got it all straightened out. If you get the drain water seperator light coming on then......
-drain the water seperator everyday, every other day.
-starting running the best diesel you can find...shell
-put additive in every tank...lucas fuel enhancer
-I do not think it is necessary to changed fuel filters unless they already needed it.
-keep draining the water seperator (catch it in a clear coke bottle so you can see what your getting) and looking at the remants. In my process of draining, it went from water in every bottle 6-7 times, then the bottles started to get better until finally they were free of water but it was still sending good fuel to the seperator.

For what it's worth to ya....It is going to take about a month/month 1/2 to get bad fuel out of the system. Maybe this will save folks from trouble.

 

Do you know which station you got the bad diesel from?

 

It was either chevron or wal-mart (I believe their brand was Murphy USA). One of the two or possibly both.

 

I doubt it was chevron, they have some of the higher self-imposed standards around. I try to fill up there at least every-other tank, and I've yet to see any water in 6500 miles. wally world, OTOH... they have terrible fuel in my experience. I stopped buying gasoline there and I will never put their diesel in my truck.