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Removing and installing fuel pressure senderG247 > < Checking fuel pressure regulating valveN276

A4 Mk2

Removing and installing fuel pressure regulating valveN276
Removing and installing fuel pressure regulating valve -N276-
Special tools and workshop equipment required
t  Torque wrench
t  Open-end spanner insert, 30 mm
t  Pliers (e.g. water pump pliers)
   
The fuel pressure regulating valve -N276--1- is located in the right-side fuel rail (cylinder bank 1). It maintains a constant pressure in the rail and the injector pipes (high-pressure fuel circuit).
If the pressure in the high-pressure fuel circuit is too high, the regulating valve opens to allow some of the fuel to flow back from the rail element to the fuel tank via a return line.
If the pressure in the high-pressure fuel circuit is too low, the valve closes and seals off the high-pressure section of the system from the low-pressure section.
The fuel pressure regulating valve -N276- cannot be re-used.
Removing
  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.
–  Remove engine cover panel → Chapter.
–  Remove intake hose between air mass meter -G70- and turbocharger.
–  Open cable tie securing wiring harness located above fuel pressure regulating valve -N276-.
–  Remove banjo bolt for fuel return lines (make sure that all parts are clean).
–  Before removal, clean area around thread for fuel pressure regulating valve using cold cleaning solution etc. (no dirt must enter the opening in the high-pressure reservoir).
  Note
Clean carefully; cleaning solution must not enter the electrical connector.
–  Dry off fuel pressure regulating valve -N276-.
  A23-10082
–  Detach electrical connector -1- on fuel pressure regulating valve -N276-.
–  Slacken union nut (counterhold at hexagon flats on housing). Then unscrew and remove by hand.
–  Extract dirt from opening in rail (threads and sealing surface). Do not use metal tools, etc.
  Note
Seal off opening in rail immediately with a suitable plug to prevent dirt from entering.
Installing
  Note
t  The fuel pressure regulating valve -N276- has a deformable sealing lip and no separate seal; it can therefore be used only once.
t  Check that sealing surfaces (deformable sealing lip) and threads on new fuel pressure regulating valve -N276- are not damaged.
t  Check sealing surface at opening in rail.
t  Thread on fuel pressure regulating valve -N276- must be free of oil and grease.
–  Screw on union nut by hand.
–  Align regulating valve so that connecting wire is free of tension after connector is attached.
–  Hold regulating valve in this position with pliers (water pump pliers or similar).
–  Use suitable torque wrench with suitable open-end spanner insert to tighten union nut.
  Note
t  There are different tightening torques for vehicles manufactured »before« November 2005 and for vehicles manufactured »after« November 2005.
t  To find out whether the vehicle was manufactured before or after November 2005: unplug electrical connector from throttle valve module -J338- and count the pins.
t  4 pins = manufactured before November 2005
t  5 pins = manufactured after November 2005
Tightening torques for vehicles manufactured before November 2005
Tighten union nut in 2 stages.
Stage 1: 60 +/-5 Nm (counterhold hexagon flats on housing).
Then back off union nut 90° (1/4 turn; counterhold hexagon flats on housing).
Stage 2: 80 +5 Nm (counterhold hexagon flats on housing).
Tightening torques for vehicles manufactured after November 2005
Tighten union nut in 2 stages.
Stage 1: 60 +/-5 Nm (counterhold hexagon flats on housing).
Then back off union nut 90° (1/4 turn; counterhold hexagon flats on housing).
Stage 2: 95 +5 Nm (counterhold hexagon flats on housing).
–  Tighten banjo bolt for fuel return lines with new seals to 25 Nm.
–  The remaining installation steps are carried out in the reverse sequence.
–  After installation, run engine at moderate speed for several minutes and then switch off.
–  Check fuel system for leaks.
–  Interrogate fault memory.
–  After completing the repair, road-test the vehicle. Accelerate with full throttle at least once. Then check the high-pressure section of the fuel system again for leaks.
–  Interrogate fault memory again.
  A23-10082

Removing and installing fuel pressure senderG247 > < Checking fuel pressure regulating valveN276