Test Y: Water-In-Fuel Indicator Always On: Description

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2001 GMC Savana Special, 2001 GMC Savana Camper Special, 2001 GMC Savana, 2001 Chevrolet RV Cutaway, and 2001 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

The fuel manager/filter assembly consists of fuel heater, water-in-fuel sensor and a filter. The filter contains the coalescer, a device that combines small droplets of water into larger ones, and the filter/separator. A fuel lift pump delivers diesel fuel from the tank to fuel filter. As fuel enters the filter, fuel passes first through the fuel heater. Heater contains a thermostatic switch. The switch opens or closes to turn heater OFF or ON, depending on temperature of the fuel. Fuel then passes through the filter. Next the fuel flows through the water coalescer. Here the droplets of water in fuel combine into larger drops and fall into the water reservoir in the filter. When fuel flows from fuel manager/filter assembly to injection pump, fuel is clean and free of water. The solid state water-in-fuel sensor supplies voltage to a probe. When the probe touches water, the module closes a switch. This completes a circuit to ground to light the water-in-fuel indicator. A time delay circuit in the water-in-fuel module grounds the indicator briefly to test the bulb each time ignition switch is turned to RUN position. Fuel heater is operated by a built-in thermostatic switch. When switch is closed, battery voltage is supplied to the heater.