The fuel pump receives fuel from the airplane fuel system. The low pressure boost stage of the pump pressurizes the fuel and sends it to the fuel/oil cooler (FOC). The fuel flows from the FOC, through the fuel pump filter element, and then to the high pressure main stage of the pump.
The high pressure main stage increases the fuel pressure and sends it to the fuel metering unit (FMU). It also supplies servo fuel to the servo fuel heater and engine components.
Fuel for combustion (metered fuel) goes through the fuel flow transmitter to the distribution valve. [Figure 2-57] The fuel distribution valve supplies metered fuel to the fuel supply manifolds. [Figure 2-58]
The fuel injectors get the metered fuel from the fuel supply manifolds and spray the fuel into the engine for combustion. [Figure 2-59]
The fuel pump housing contains a disposable fuel filter element. The fuel filter differential pressure switch supplies a signal to the EEC that indicates an almost clogged filter condition. Unfiltered fuel can then bypass the filter element if the element becomes clogged.