BOOT 1166202 - Caterpillar

The duplex fuel filter system enables you to change the filter elements while the engine is running.
Illustration 1 g01344340
(1) Control valve handle
(2) Fill valve During normal operation, the control valve should be in the Main Run position. In this position, the fuel is cleaned by the filter elements in the main filter housing. The auxiliary filter elements can be changed at this time after the fuel pressure is released and the auxiliary housing is drained.
Illustration 2 g01344374
(1) Control valve handle
(2) Fill valve When the control valve is moved to the Auxiliary Run position, the fuel will be cleaned by the filter elements in the auxiliary filter housing. The main filter elements can be changed at this time after the fuel pressure is released and the main filter housing is drained.After the filter elements in either housing have been changed, the housing must be filled with fuel in order to keep the engine speed and the fuel pressure constant when the flow of fuel is directed from one filter housing to the other filter housing. To fill either filter housing with fuel, move fill valve (2) to the open position for a minimum of five minutes. This will direct a small flow of fuel to the empty filter housing. Some air will remain in the filter housing until the control valve directs fuel flow through the housing. The remainder of the air in the system is then directed back to the fuel tank by the pressure regulating valve that is attached to the front of the right fuel manifold.
Illustration 3 g01344383
(1) Control valve handle When the control valve is in the Both Run position, the fuel is cleaned by the main filter elements and by the auxiliary filter elements. This position should only be used when it is necessary.