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Check power consumption > < Inspecting proper operation and power supply

Octavia Mk2

Check fuel flow rate
Check fuel flow rate
Test conditions
l  Supply voltage o.k.
l  Fuel pressure regulator and holding pressure o.k.
Work procedure
–  Switch off the ignition and all electrical components and take out the ignition key.
–  Removing rear seat bench → Body Work; Rep. gr.72.
–  Remove the cover from the fuel delivery unit.
  Note
For vehicles with auxiliary heating, the plug connection for the dosing pump -V54- must be disconnected additionally.
   
–  First of all check the plug connection -arrow- for correct fit. To do so, pull on the plug connection without pressing the catch. If the plug connection was not correctly positioned, this could cause a fault.
–  Disconnect the plug connection -arrow- from the fuel delivery unit.
–  Check the contacts at the plug and at the fuel delivery unit for damage.
  N20-10623
–  Connect the adapter for measuring method/DSO (5-pin) -VAS 5565- to the plug and to the fuel delivery unit.
–  Connect the remote control -V.A.G 1348/3A- to the adapter -VAS 5565- and to the battery positive (+).
  Note
t  This step is only intended to ensure that the fuel delivery unit runs when the engine is switched off.
t  The fuel flow rate of the fuel delivery unit is measured at 0.4 MPa (4 bar). Therefore the fuel pressure must be checked before measuring the fuel flow rate.
  WARNING
The fuel system is under pressure! Before opening the system lay cleaning cloths around the connection point. Reduce pressure by carefully releasing the connection point.
  N20-10422
–  Detach return-flow line -1- from fuel pressure regulator.
  Note
Press in the securing ring in order to unlock the fuel line.
–  Connect adapter -V.A.G 1318/17- at fuel pressure regulator and hold the end of the adapter in a measuring vessel.
–  Operate remote control -V.A.G 1348/3A- for about 5 seconds, in order to fill up the fuel filter.
–  Drain the measuring vessel.
–  The fuel flow rate of the fuel delivery unit is dependent on the voltage. Therefore, connect the multimeter -V.A.G 1715- to the terminals -1 and 5- of the adapter for measuring method/DSO (5-pin) -VAS 5565-.
–  Activate remote control for 30 seconds while measuring the battery voltage.
  S20-0203
–  Compare the fuel rate with the specified value.
*) Minimum flow rate cm 3/30 s
**) Voltage at fuel delivery unit when engine not running and delivery unit operating.
Read out examples:
During the test a voltage of 10.5 V was measured. Thus a minimum flow rate of 580 cm3/30 s is obtained.
If the minimum flow rate is not reached:
–  Check the feed line to the filter for possible restrictions (kinks) or blocking.
If the fuel line is O.K.:
–  Check the fuel flow rate before the fuel filter.
  WARNING
The fuel feed line is pressurized! Place cleaning cloths around the connection point before detaching hose connections. Reduce pressure by carefully removing the hose.
  S20-0268
–  Disconnect the feed line -1- from the fuel filter inlet.
  Note
Press in the securing ring in order to unlock the fuel line.
–  Connect pressure measuring device -V.A.G 1318- with adapter set -V.A.G 1318/17- as shown.
–  Fit adapter -V.A.G 1318/1- onto adapter -V.A.G 1318/11- of pressure measuring device and hold in a measuring vessel.
–  Open shut-off cock of the pressure measuring device. The lever then points in the direction of flow -A-.
–  Activate remote control -V.A.G 1348/3A-. Slowly close the shut-off cock until the manometer displays 0.4 MPa overpressure (4 bar). Do not make any further changes to the position of the shut-off cock.
–  Drain the measuring vessel.
–  Activate remote control again for 30 seconds. Compare the fuel flow rate with the value determined during the first measurement.
If the minimum flow rate is now reached:
–  Replace fuel filter.
If the minimum flow rate is again not reached:
–  Remove fuel delivery unit and inspect filter strainer for soiling.
If you have still not found any fault up to this stage:
–  Replace fuel delivery unit.
–  Connect all released fuel lines.
–  Venting air from the fuel system → Chapter.
If the required fuel delivery volume has been achieved, but a fault is still suspected in the fuel supply system (e.g. intermittent breakdown of the fuel supply):
–  Check power consumption of the fuel pump → Chapter.
  S20-0205

Check power consumption > < Inspecting proper operation and power supply