D 350 Pickup L6-359 5.9L DSL (1989)
Fuel Heater: Description and Operation
Water-In-Fuel Sensor R & R
The fuel heater is located in the top of the fuel/water separator filter adapter, and is used to prevent the diesel fuel from waxing inside the filter assembly.
The heater has a built-in temperature sensor that monitors the fuel temperature and turns the heater ON and OFF depending on the temperature. The
heater is turned ON if the fuel temperature is less than or equal to 43~F (6~C), and is turned OFF if the fuel temperature is greater than or equal to 53~F
(13.5~C). The fuel heater receives voltage from the ignition switch.
