My fuel filter/water seperator has got the place to plug in the two wires at the top of the fuel filter, but I think there is a place to plug two at the bottom that is missing, because I have two wires there with nothing to plug them in to. I get an occasional water in fuel light blinking, and was wondering if it is real without those wires hooked up. Also, where might one find the bottom part without paying a fortune. Maybe that makes a little sense.

 

The two wires at the top are for the fuel heater.

It sounds like you have a filter with no provision for a WIF sensor, or the wires got ripped off it. You can get the right filter and a WIF sensor from Cummins or from Geno's Garage.

 

Does the heater for the fuel filter heat all the time or is it on a thermostat?

 

I purchased a new WIF for my truck last year and I want to say it was around $20,not real ex.

 

Just use Fleetgaurd LS1221, with none of that wires-hanging mess on them, twice as long, and fit like a glove.

If the WIF light is coming on, with the plug not connected, moisture, or something, is shorting across the connections in the loose plug, just like water makes the circuit in a working water-in-fuel sensor.

 

It has a thermostatic switch inside. When the fuel temp is under 59 degrees it turns on.

 

I made a minor error in my filter number.

The correct number is FS1221, not LS1221.