6.2 fuel filter assembly how does it work?

[87J]

I have a thirst to know how everything works but dont want to take mine apart until I have to. Cant find much info on it in the manuals, I know the top 2 wires are fuel heater. The schematics show a vaccum switch and water in fuel solenoid but doesnt show how it all works together. What makes the water in fuel light stay on for a couple seconds when ignition is turned on? seems to me like there has to be a timer or module somewhere...

 

[87J]

No takers??? Still curious about this.

 

[Warthog]

There are two sensors and one solenoid/relay on the stock CUCv fuel filter.

1. Pressure/vacuum sensor behind the filter - Diagram E-11 - Known to leak and is only used with the STE/ICE diagnostic system. Many have disconnected it and plugged the hole for the sensor
2. Fuel Heater - Diagram E-20 - It is powered by the wiper fuse and is on anytime the key is on
3a. Water-in-Fuel solenoid - Diagram E-1 Gets power when the key is in the START position via the purple/white wire with the black as ground.



3b. Water-in-Fuel light - Diagram E-3 and E-4 - I have never taken apart the WIF solenoid but I think this is how it works.

When the solenoid closes it completes the circuit for the light. Power is supplied to the light via the pink/black wire Circuit 139A in diagram E-4. It goes thru the light and on to the solenoid via the yellow 50B wire diagram E-3. (the big IF) If there is water in the fuel then the ground circuit closes and the light comes on.

Power is also supplied via the pink/black wire 39A (diagram E-4 and E-3)

This is a big guess but there may be a timer in the solenoid that turns the light on for a few seconds.

 

[Cucvnut]

Kill it with fire and get a spin on filter.

 

[Warthog]

Found this diagram on a diesel page

 

[87J]

Thanks a lot warthog I had been studying the schematics for awhile and came up with similar theory but that diagram you found answers all my questions! I would have never thought there to be a module inside there.