Circuit Description

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