My water-in-fuel light has been on constantly since I bought my 6.0L X about 3 weeks ago. Replaced fuel filters immediately; used DieselKleen in fuel; drained the HFCM multiple times...no water (upgraded the HFCM plug too). Sprayed some carb cleaner through drain hole and out runs red goo. Finally had time to clean out the HFCM this weekend.

1. Raised front-end on ramps, chocked wheels.
2. Attempted to remove front drive shaft to 4x4. Couldn't free one of the bolts on the front U-joint. Rats.
3. Since I couldn't remove the drive shaft, there wasn't enough room to remove the entire HFCM, so I removed only the cover.
4. Disconnect battery.
5. Unplug WIF sensor and fuel heater.
6. Drain HFCM (again) to make sure it's empty...it wasn't.
7. Disconnect 4 fuel lines. Wipe fuel from running down arms. I should mention that I had less than 1/4 tank of fuel to try and minimize spillage.
8. Remove 4 cover screws (7mm, though my 5/16" SAE socket fit better.)
9. Clean cover and HFCM with carb cleaner.
10. Replace HFCM gasket.
11. Replace HFCM cover; screws were hand-tightened.
12. Reconnect fuel lines and sensors.
13. Cycle Key-On, Engine Off (KOEO) about 4-5 times.
14. Crank 'er up....no more WIF light.

Here are some before and after pics.

BEFORE:




AFTER:

 

One more thing: I wouldn't have attempted, much less couldn't have done it without tips and other how-to's on FTE. Thanks guys!

 

Nasty stuff!

Was it mold?

 

Not sure if it was mold or algae. Nasty for sure!