Diesel Filter heater
 

I have a 1999 F-350 with the Turbo V-8 7.3 liter engine.
I'd like to know the following about the fuel heater located in the filter housing;
1. How does it work?
2. How can you verify it is working?
3. What can I expect it to do?

This AM is was cold enough that the fuel was thick (or waxing) The truck would only move in Low and then at less than 6 MPH. I had to park it.
Thank you!
Eric

The system is a 'return to tank' flow so the fuel is circulated when the pump runs. The fuel heater is activated when the key is cycled to run/start. It will continually heat the fuel as the system circulates as well as heat the fuel contained in the fuel filter/separator housing during glow plug cycle times (wait to start).

The power distribution to the heater connector is on the red/light green wire. You can check for 12v there, which there should be since its a shared circuit with the PCM/IDM relays. Usually when the heaters fail, they tend to come loose (if the original) from their mounting plate and short, blowing the fuse causing the truck to not start. Or, you may try a simple ohm's test to see if the heater is open. The heater and water in fuel sensor are a unit. Depending on 'how' cold, plugging the block heater in is a help if its equipped with a cord.

Hayapower,
Great!
Thank you for he info. Regards,
Eric