Fuel supply, function

P07.70-2062-12

18 Rail

19 Adapter

20 High-pressure pump

20/1 Drive plate (drive)

20/2 Test connection for low pressure fuel line

55/1 Fuel filter with integrated fuel pressure regulator

75 Fuel tank

B4/6 Rail pressure sensor

M3 Fuel pump (in fuel tank)

Y74 Pressure control valve

Y76 Fuel injectors

a Low pressure fuel line from fuel pump (connecting line in fuel tank)

b Fuel line to fuel filter with integrated fuel pressure regulator

c Fuel return line from fuel pressure regulator in fuel tank

d Low pressure fuel line to adapter

e Low pressure fuel line to high pressure pump

f High pressure fuel line to rail

g Fuel return line from rail (pressure regulator valve) to adapter

The fuel supply supplies filtered fuel out of the fuel tank in adequate amounts under all operating conditions at an adequate pressure to the fuel injectors.

The fuel pump suctions the fuel from the fuel tank and delivers it through the fuel filter and the fuel pressure regulator (over the adapter) to the high pressure pump. In doing so the low fuel pressure is limited by the pressure limiting valve to approx. 3.8 bar. Excess fuel flows from fuel pressure regulator back into fuel tank.

The high pressure pump compresses the fuel up to an operating pressure of 30 to 120 bar and pumps it into the rail. The ME-SFI [ME] control unit (N3/10) regulates the fuel high pressure in the rail in line with the map by means of the pressure control valve. The fuel return from the pressure regulator valve is led over the rail to the adapter and made available to the high pressure pump again for compacting.

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The fuel low pressure (about 3.8 bar) which is regulated by the fuel pressure regulator can be measured at the test connection or checked.