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Venting air from the fuel system > < Checking fuel operating pressure

Fabia Mk1

Inspecting the non-return valve of the fuel delivery unit and holding pressure
Inspecting the non-return valve of the fuel delivery unit and holding pressure
Test conditions
l  Pressure gauge -V.A.G 1318- connected → Chapter
  Note
This test simultaneously checks the tightness of the connections of the fuel feed line from the fuel delivery unit through to the connecting point of the pressure gauge -V.A.G 1318-.
   
–  Shut-off cock on measuring device in position -A- open.
For vehicles with 3 bar fuel pressure regulators
–  Activate remote control until an overpressure of at least 0,28 MPa (2,8 bar) is built up.
–  Disconnect the remote control and observe the pressure drop on the pressure gauge. The pressure must not drop below 0,25 MPa (2,5 bar) after 10 minutes.
If the pressure still drops:
–  Activate the remote control until an overpressure of at least 0,28 MPa (2,8 bar) is built up, and simultaneously close the shut-off cock on the measuring device in position -B-.
If the pressure does not drop:
–  Test fuel distributor for tightness.
If the pressure again drops:
–  Check line connections for leaktightness.
If the lines are not found to be faulty:
  S20-0106
–  Connect the pressure gauge -V.A.G 1318- with adapter -V.A.G 1318/11- and -V.A.G 1318/17- to the black feed line from the pump to the fuel filter (old version filter shown with integrated fuel pressure regulator). For the new version of the filter with disassembled fuel pressure regulator the black feed line is connected to the fuel filter outer connection.
–  Open shut-off cock on the measuring device -position A-.
–  Activate the remote control and simultaneously close the shut-off cock in the measuring device in position -B-.
–  After reaching min. 0.28 MPa (2.8 bar), disconnect the remote control and observe the drop in pressure on the pressure gauge. The pressure must not drop below 0,25 MPa (2,5 bar) after 10 minutes.
If the pressure still drops:
–  Check the connections of the fuel lines for tightness.
If wiring is o.k.:
–  Replace fuel delivery unit.
If the pressure does not drop and the delivery unit is O.K.:
–  Replace the fuel pressure regulator.
For vehicles with 4 bar fuel pressure regulators
–  Activate remote control until an overpressure of at least 0.37 MPa (3.7 bar) is built up.
–  Disconnect the remote control and observe the pressure drop on the pressure gauge. The pressure must not drop below 0.34 MPa (3.4 bar) after 10 minutes.
If the pressure still drops:
–  Activate the remote control until an overpressure of at least 0.37 MPa (3.7 bar) is built up, and simultaneously close the shut-off cock on the measuring device in position -B-.
If the pressure does not drop:
–  Test fuel distributor for tightness.
If the pressure again drops:
–  Check line connections for leaktightness.
If the lines are not found to be faulty:
  S20-0105
–  Connect the pressure gauge -V.A.G 1318- with adapter -V.A.G 1318/11- and -V.A.G 1318/17- to the black feed line from the pump to the fuel filter (old version filter shown with integrated fuel pressure regulator). For the new version of the filter with disassembled fuel pressure regulator the black feed line is connected to the fuel filter outer connection.
–  Open shut-off cock on the measuring device -position A-.
–  Activate the remote control and simultaneously close the shut-off cock in the measuring device in position -B-.
–  After reaching 0.37 MPa (3.7 bar), disconnect the remote control and observe the drop in pressure on the pressure gauge. The pressure must not drop below 0.34 MPa (3.4 bar) after 10 minutes.
If the pressure still drops:
–  Check the connections of the fuel lines for tightness.
If wiring is o.k.:
–  Replace fuel delivery unit.
If the pressure does not drop and the delivery unit is O.K.:
–  Replace the fuel pressure regulator.
  S20-0105

Venting air from the fuel system > < Checking fuel operating pressure