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Bleeding fuel system > < Overview of fitting locations

A3 Mk2

System layout
System layout
  WARNING
t  Always read rules for cleanliness and instructions for working on fuel system → Chapter.
t  Follow these instructions and rules for cleanliness before starting work and while working on the fuel system.
  Caution
The high-pressure pump has very close tolerances and must not be allowed to run without fuel. To prevent this and to enable the engine to start quickly after parts have been renewed, it is important to observe the following:
t  If components of the fuel system between the fuel tank and the high-pressure pump are removed or renewed, the first fuel filling operation must be performed.
t  If a fuel pump, fuel line (between fuel tank and high-pressure pump) or fuel filter is removed or renewed, the fuel system must be bled before the engine is started for the first time.
t  If the high-pressure pump is removed or renewed, the fuel system must be bled before the engine is started for the first time.
t  Perform first fuel filling after installing high-pressure pump → Chapter.
  Note
The high-pressure pump will be damaged if the first filling procedure is not performed.
   
1 - Fuel tank
q   With fuel system pressurisation pump -G6-
2 - Fuel filter
q   Fuel filter - exploded view → Rep. gr.20
q   Renewing fuel filter → Rep. gr.20
3 - High-pressure pump
q   After renewing, first fuel filling MUST be performed (it is important not to allow pump to run while it is still empty) → Chapter
q   After renewing high-pressure pump or fuel pressure regulating valve -N276-, learnt values must be re-adapted; see „Guided Functions“ in vehicle diagnostic tester
q   Removing and installing → Chapter
4 - Fuel metering valve -N290-
q   Do not unscrew
5 - Fuel pressure sender -G247-
q   Removing and installing → Chapter
q   100 Nm
6 - Fuel rail
7 - Fuel pressure regulating valve -N276-
q   Cannot be re-installed
q   After renewing high-pressure pump or fuel pressure regulating valve -N276-, learnt values must be re-adapted; see „Guided Functions“ in vehicle diagnostic tester
q   Removing and installing → Chapter
q   80 Nm
8 - Pressure retention valve
q   The pressure retention valve maintains a residual pressure in the fuel return lines (required for control function).
q   The pressure retention valve may only be renewed together with the fuel return lines.
9 - Injectors
q   Removing and installing → Chapter

   

Bleeding fuel system > < Overview of fitting locations