General information
The fuel system consists of a fuel tank located at the rear under the car body, an electric fuel pump immersed in the fuel tank, a fuel filter, fuel supply and return lines. The fuel pump supplies fuel to the fuel rail, which functions as a common reservoir for four injectors that inject fuel into the intake tracts of the cylinders. Before entering the rail, the fuel passes through a filter.
On M43TU and M52TU engines, the fuel pressure regulator is mounted on the fuel rail. On N42 and M54 engines, the fuel pressure regulator is built into the fuel filter (Fig. 1.1). The fuel injection system is described in more detail in paragraph 7, and the exhaust system in paragraph 14.
Fig. 1.1. Fuel system
A Engines M43TU and M52TU
In Engines N42 and M54
1 Fuel tank
2 Electric pump
3 Calming chamber
4 Pressure limiting valve
5 Safety valve
6 Drain pump
7 Expansion tube of the tank
8 Shut-off valve
9 Filler neck
10 Filler cap
11 Ventilation hose
12 Pressure pipeline
13 Fuel return line
14 Ventilation hose
15 Ventilation hose
17 Expansion tank
18 Rollover protection valve
20 Fuel filter
21 Fuel pressure regulator
23 Fuel rail with injectors
24 BZU
25 Intake manifold
26 Tank ventilation valve
27 Blow-off pipe
28 Ventilation duct
30 Fuel vapor release pipe
31 Carbon absorber
Cautions
Warning! Many of the operations described in this chapter involve disconnecting fuel lines, which may result in some fuel being spilled. Before starting work, read and follow the warnings given in the "Safety First!" section at the beginning of this book. Gasoline is volatile and extremely dangerous, so no precautions are too great when working with it.
Caution! Excess pressure remains in the fuel system long after the engine has stopped. Therefore, before disconnecting any fuel line, release the pressure in the system as described in paragraph 8.
Information taken from this resource BMWMAN.RU