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Checking fuel delivery unit > < Checking feed pressure of tandem pump, vehicles with engine identification characters BMM

Octavia Mk2

Checking the tandem pump for tightness (internal)
Checking the tandem pump for tightness (internal)
  Note
After re-installing an already used tandem pump e.g. after changing or repairing the cylinder head and/or after changing an engine without component parts, the tandem pump must be absolutely checked for internal tightness between fuel and oil part. In case of leakage fuel and oil can be mixed, which can cause an engine damage.
Special tools and workshop equipment required
t  Tester, e. g. -V.A.G 1687-
Procedure
–  Disconnect the fuel intake hose (white marking) and the fuel return-flow hose (blue marking) from the tandem pump.
–  Close fuel return-flow connection at tandem pump with a plug. Secure plugs with spring strap clips.
Prepare tester -V.A.G 1687- as follows:
   
–  Unscrew pressure control valve -2- fully and close the valves -3- and -4-.
–  Connect test connection -5- with a commercially available connection for compressed air und a piece of fuel hose to the connection of the fuel feed line for the tandem pump. Secure connection with spring strap clips.
  Note
The rotary knob must be pulled to the top in order to rotate the pressure control valve -2-.
–  Connect the pneumatic hose -1- (pneumatic support) at tester.
  Note
If there is water in the transparent water drain reservoir, drain water via the drain plug -6-.
–  Open valve -3-.
–  Set the pressure to 0.1 MPa (1.0 bar) with the pressure control valve -2-.
  WARNING
The maximum test pressure is 0.13 MPa (1.3 bar) and it must not be exceeded.
  V21-0168
–  Open valve -4- and wait until the test circuit is filled up. If necessary readjust pressure to 0.1 MPa (1.0 bar).
–  Close the valve -3- to maintain the pressure and observe the drop in pressure for 1 minute.
If the pressure does not drop, the tandem pump can still be used.
   In case of drop in pressure the tandem pump must be replaced.
  V21-0168

Checking fuel delivery unit > < Checking feed pressure of tandem pump, vehicles with engine identification characters BMM