THEORY OF OPERATION
ENGINE COMPONENTS (Continued)
Fuel Filters, Fuel/Water Separator Filter (Continued):
Fuel enters both coalescer (outer) elements simultaneously from the inside and passes through
the element walls to the outside. The separated fuel and water fill the collection chamber.
Water, which has a higher specific gravity, sinks and collects at the bottom of the chamber.
The separated fuel, floating on the water, passes through the center element (final fuel filter)
from the outside inward and then out of the separator filters assembly through a hose to the
fuel injection pump.
Water removed from the fuel by the separator filter is drained automatically as needed. Two
water-sensing electric probes act as water-activated switches. When the collection chamber
water level reaches the upper probe, an electric circuit is closed to a solenoid-operated dump
valve located on the lower left side of the engine. The solenoid valve opens and water is
drained via a hose from the separator filter through the valve. When the separator water level
goes below the lower probe, the electric circuit to the solenoid drain valve is opened, and the
Both the primary filter and the fuel/water separator filter incorporate top-mounted bleeder
valves to assist in the removal of air from the fuel system.
WP 0004 00-18