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Check fuel flow rate > < Check fuel pressure

Octavia Mk2

Test holding pressure
Test holding pressure
   
l  Fuel pressure O.K. and pressure gauge -VAS 6550- connected in the engine compartment → Chapter.
–  Switch the ignition on and off so often until the fuel pressure on the pressure gauge does no longer rise.
–  Read off fuel pressure on the pressure gauge.
l  Specified value: 0.58 ... 0.70 MPa (5.8 ... 7.0 bar)
–  Observe pressure drop at pressure gauge.
l  The pressure must not drop below 0.3 MPa (3.0 bar) after 10 minutes.
If the pressure still drops:
–  Switch the ignition on and off so often until the fuel pressure on the pressure gauge does no longer rise.
  N20-10628
–  Immediately close the shut-off cock -B- of the pressure gauge after the pressure has built up. The lever points at right angles in the direction of flow.
Now the pressure does no longer drop:
  Note
Search for leakage on the engine side. Repeat the holding pressure test. This time, close the shut-off cock -A- in order to determine if a leak is indeed present on the engine side.
–  Check the low-pressure line to the high pressure pump.
If no fault is found:
–  Replace high pressure pump → Chapter.
If the pressure again drops:
Search for leakage on the fuel tank side, to do so proceed in the following manner:
–  Check the fuel line to the fuel filter for tightness.
If the fuel line is not found to be faulty:
–  Check the pressure holding valve in the fuel delivery unit. To do so proceed in the following manner:
  S20-0349
–  Disconnect fuel feed line -arrow- at fuel filter.
  N20-10629
–  Connect the pressure gauge -VAS 6550- with the adapter -VAS 6550/1- and -VAS 6550/2- between the fuel filter and the fuel feed line.
–  Make sure that the discharge cock is opened and the shut-off cocks are opened.
–  Switch the ignition on and off so often until the fuel pressure on the pressure gauge does no longer rise.
–  Read off fuel pressure on the pressure gauge.
l  Specified value: 0.58 ... 0.70 MPa (5.8 ... 7.0 bar)
  N20-10630
–  After the pressure has built up, close the shut-off cock -A-.
–  Observe pressure drop at pressure gauge.
l  The pressure must not drop below 0.3 MPa (3.0 bar) after 10 minutes.
If the pressure drops:
–  Non-return valve in the fuel pump faulty, replace fuel delivery unit → Chapter.
If the pressure does not drop:
–  Pressure limiting valve in the fuel filter defective, replace the fuel filter.
  S20-0349

Check fuel flow rate > < Check fuel pressure