my water in fuel warning keeps going off, but I can find no evidence of water in the system.

how is water detected and what triggers the warning?

if there is water in the fuel system, what is the best way to resolve the warning? I just replaced the fuel filter about 8k ago.

 

You have to drain the water separator that's down on the frame rail where the primary fuel filter is. Its very easy, all you need is a 6mm allen wrench. If you have already drained it multiple times and the warning keeps coming back, then the sensor is probably bad

 

haven't drained it yet, but that was my next step

 

You should drain it at a minimum of every fuel filter change and that is 15,000 miles. Use only OEM filters.

 

Try this. Take lower fuel filer out , buy at least 2 cans of brake cleaner. Take the drain bolt out and clean out the housing the filter sits in. Most likely you have a lot of debris in there causing false positive warning lamp. Then use compressed air to vclear out any asdditional debris and to dry up any left over brake cleaner then reassemble. Had same problem on 4.5 lcf that the warning lamp was always illuminated and after cleaning out the housing it cleared the lamp.

Also the filter should be changed around every other oil change. The truck I mention the fuel filters were severely neglected and the lower was black and the upper was starting to disintegrate and twist

 

Oops I missed that he hasn't tried to drain water via plug first

 

Get the updated drain valve while you at it, makes life a hell alot easier. No stripped 6mm allen holes just hand tighten with the new valve

 

Make sure you use OEM Motorcraft fuel filter. Its got a film over it that catches the water.

 

I already have the updated drain valve and I ONLY use Motorcraft filters (oil/fuel)

draining water seperator now. If that fails, I will clean the inside of the housing and replace the fuel filter.

 

The manual calls for 15,000 mile intervals. I have done mine early in the past if a trip will put me outside the recommendation. Knock on wood, my filters have always looked good and I've never had a wif light.

 

you are correct! , I was going off of severe duty service intervals. it might just be me, but i have always gone by the severe duty service intervals for every vehicle i have owned. I never have changed oil at 5k. maybe I am wasting my money

 

so I drained the water separator yesterday and found some water in the bottom of the pan. drove the truck around for some errands and WIF warning came back. went to the parts store and picked up a bottle of Diesel power service water remover/fuel conditioner and added about a half a bottle, WIF warning has not come back on, yet.

fuel filter will get changed next engine oil change.

 

One trick that sometimes works is to bend a WD40, PowderBlast, or equivalent cleaner "spray straw" to a 90 degree angle - about 1/2 inch long on the end. Insert the bent staw into the opening where the drain plug goes. Spray the cleaner into the HFCM for a few seconds and then let drain. Repeat a few times. This can clean out moisture and algae, etc.

If the WIF light is persistent, you may need to take the HFCM cover off and clean it that way.