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Checking delivery rate of fuel pump > < Removing and installing fuel pressure regulating valveN276

A3 Mk2

Removing and installing fuel pressure senderG247
Removing and installing fuel pressure sender -G247-
   
The fuel pressure sender -G247--1- is located in the fuel rail and continuously measures the fuel pressure in the high-pressure system. It transmits a corresponding voltage signal to the engine control unit -J623-.
Should the sender fail, the engine control unit will control the fuel pressure via a mapped open-loop backup function, allowing a maximum of approx. 3000 rpm.
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.
–  Before removal, clean area around thread for fuel pressure sender using commercial cleaning solution etc. (no dirt must enter opening in fuel rail).
  Note
Clean carefully; cleaning solution must not enter the electrical connector.
–  Dry off fuel pressure sender -G247-.
  A23-10420
–  Unplug electrical connector -1- at fuel pressure sender -G247-.
–  Unscrew fuel pressure sender -G247-.
–  Extract dirt from opening in fuel rail (thread and sealing surface) using a vacuum cleaner. Do not use metal tools, etc.
  Note
Seal off opening in fuel rail immediately with a suitable plug to prevent dirt from entering.
Installing
  Note
t  The fuel pressure sender -G247- does not have a seal; instead, it has a deformable sealing lip.
t  Check that sealing surfaces and thread on fuel pressure sender -G247- are not damaged. If inspection of fuel pressure sender -G247- shows that it is OK, it can be used again.
t  Also check sealing surface at bore.
t  The beginning of the thread and the deformable sealing lip of the fuel pressure sender -G247- must be lubricated with diesel fuel.
–  Screw in fuel pressure sender -G247- by hand.
–  Then tighten fuel pressure sender -G247- to specified torque.
t  Tightening torque: refer to fuel system - exploded view → Chapter
After installing fuel pressure sender -G247-, leave engine running at moderate speed for a few minutes when bleeding fuel system and then switch off again.
  Note
The fuel system is „self-bleeding“; do NOT open the high-pressure connections.
–  Interrogate event memory.
–  Switch off ignition.
–  Carefully check the entire fuel system for leaks.
Renew affected component if leakage still occurs after tightening to correct torque.
–  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.
  Note
If there is any air left in the fuel system, the engine may switch to the backup mode ('emergency running' mode) during the road test. Switch off the engine and erase the event memory. Then continue the road test.
–  After road test, interrogate event memory again.
  A23-10420

Checking delivery rate of fuel pump > < Removing and installing fuel pressure regulating valveN276