Ford Transit 2002 Owner's Manual page 842

10
11 -
The fuel sucked in by the transfer pump passes from the transfer pump through a bore into
the high pressure chamber.
The fuel metering valve is located in the bore between the transfer pump and the high
pressure chamber.
Depending on operating conditions, and under the control of the PCM the electronically
controlled fuel metering valve changes the cross section of the bore and thus the quantity of
fuel which passes into the high pressure chamber.
Transfer pump
Item Part Number
1 -
2 -
The transfer pump (a vane cell pump) is mechanically driven by the pump driveshaft.
The transfer pump sucks fuel from the fuel tank under vacuum which depends on the engine
speed and supplies it to the high pressure chamber.
There is a pressure control valve located in the low pressure circuit between the transfer
pump and the high pressure chamber, and this limits the transfer pressure.
Low pressure fuel return
The low pressure fuel return has the following functions:
Cooling and lubrication of the high pressure pump by internal return of the low pressure
fuel to the fuel tank.
Return of the leak-off fuel from the injector valves to the fuel tank.
Fuel is continually supplied to the high pressure chamber during an acceleration phase.
At the same time, some of the fuel is used to lubricate the pump and runs through the
venturi nozzle and the fuel return line back into the tank.
The venturi nozzle in the fuel return line operates according to the venturi pump principle.
The nozzle creates a slight vacuum in the leak-off line, the leak-off fuel is sucked in and is
therefore removed more easily.
High pressure chamber
Input shaft
Description
High-pressure side
Suction side
http://vnx.su