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Fuel system - exploded view (CAPA) > < System layout

A4 Mk3

Fuel system - exploded view (CAMA, CAMB, CCWA, CCWB, CGKA, CGKB, CCLA)
Fuel system - exploded view (CAMA, CAMB, CCWA, CCWB, CGKA, CGKB, CCLA)
  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
To prevent the high-pressure fuel pump from running while it is empty and to ensure that the engine starts quickly after parts have been renewed, it is important to observe the following:
If components of the fuel system between the tank and the high-pressure fuel pump are removed or renewed, the basic setting „Checking fuel system pressurisation pump“ must be performed to bleed the fuel system.
If a fuel pump, fuel line (between fuel tank and high-pressure fuel pump) or fuel filter is removed or renewed, the fuel system must be bled before the engine is started for the first time.
If the high-pressure fuel pump is removed or renewed, the fuel system must be bled before the engine is started for the first time.
Procedure for first fuel filling → Chapter
   
1 - Fuel return line
q   To fuel tank
q   Fuel return line must not be kinked, damaged or clogged
2 - Fuel supply line
q   From fuel filter
3 - Banjo bolt for fuel return line
4 - Fuel temperature sender -G81-
5 - Bolt
6 - Bracket
7 - Fuel pressure regulating valve -N276-
q   Located on cylinder bank 1
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
8 - Bolt
9 - Bracket
10 - High-pressure fuel pipe
q   Between high-pressure pump and fuel rail
11 - High-pressure fuel pipe
q   Between fuel rail on cylinder bank 1 and fuel rail on cylinder bank 2
q   When re-installing high-pressure fuel pipe, check taper seats visually for damage, scores and corrosion (always renew if damaged)
q   If high-pressure pipe is not OK, always renew high-pressure pipe
12 - High-pressure fuel pump
q   With fuel metering valve -N290-
q   After renewing high-pressure pump, 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   High-pressure pump - exploded view → Chapter
q   Removing and installing → Chapter
13 - Fuel return lines
q   The fuel return lines must not be dismantled; if necessary they must be renewed complete with pressure retention valve.
q   After replacement, engine must be run at idling speed for approx. 2 minutes to bleed fuel system. Then check fuel return lines for leaks.
14 - Bolt
q   Cover for injector on cylinder head cover
q   5.5 Nm
15 - Cover for injector
16 - Clamping piece
q   If they are to be re-installed, the injectors and clamping pieces must always be re-fitted on the same cylinder.
q   When an injector is renewed, the corresponding clamping piece must be renewed at the same time
17 - Hexagon flange nut
q   For clamping piece
q   10 Nm
18 - Bolt
q   For fuel rail on cylinder bank 2
q   22 Nm
19 - Fuel pressure sender -G247-
q   30 Nm
q   Located on cylinder bank 2
q   Removing and installing → Chapter
20 - Seal
q   Renew
21 - High-pressure fuel pipes
q   For cylinder bank 2
q   25 Nm
22 - Fuel rail
q   For cylinder bank 2
23 - Seals
q   Renew
24 - Hexagon flange nut
q   For clamping piece
q   10 Nm
25 - Injector
q   Removing and installing → Chapter
26 - Bolt
q   Cover for injector on cylinder head cover
q   5.5 Nm
27 - Cover for injector
28 - Seal
q   Renew
29 - High-pressure pipes
q   For cylinder bank 1
30 - Bolt
q   For fuel rail on cylinder bank 1
q   22 Nm
31 - Fuel return lines
q   The fuel return lines must not be dismantled; if necessary they must be renewed complete with pressure retention valve
q   After replacement, engine must be run at idling speed for approx. 2 minutes to bleed fuel system. Then check fuel return lines for leaks
32 - Pressure retention valve
q   In fuel return lines from cylinder banks 1 and 2
q   The pressure retention valve maintains a residual pressure of approx. 10 bar in the return lines
q   This residual pressure is required for the control function of the piezo injectors
q   The pressure retention valve may only be renewed together with the fuel return lines
q   After replacement, engine must be run at idling speed for approx. 2 minutes to bleed fuel system
q   Checking pressure retention valve → Chapter

   

Fuel system - exploded view (CAPA) > < System layout