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Check the fuel pump non-return valve > < Test operation and battery supply

Leon Mk2

Test fuel flow
Test fuel flow
Test conditions
l  Voltage supply, correct.
l  Remote control -V.A.G. 1348/3A-, connected.
Testing process
–  Remove the plug from the fuel filler hole.
  Caution
The fuel system is under pressure. Before opening the system, place a cloth around the connecting joints. Next, bleed the pressure by carefully loosening the connection.
–  Remove the supply hose (black colour) and use a cloth to collect the fuel that comes out.
   
–  Attach the pressure tester -V.A.G. 1318- to the fuel supply hose using the adapter -V.A.G. 1318/1-.
–  Attach the -V.A.G. 1318/13- with adaptor -V.A.G. 1318/7- to the pressure tester and place the end in a measuring glass.
–  Open the pressure tester flow valve. The lever will indicate the direction of flow -A-.
–  Operate the remote control -V.A.G. 1348/3A-, slowly closing the flow valve until the pressure gauge shows a reading of 3 bar. From that moment on, do not move the flow valve's position.
–  Empty the measuring glass.
–  The fuel pump's flow depends on battery voltage. Therefore the multimeter must be attached to the vehicle's battery using auxiliary cables -V.A.G. 1594-.
–  Operate the remote control for 30 seconds, while measuring battery voltage.
  N20-0117
–  Compare the flow obtained with the theoretical value.
-*- Minimum flow cm³/30 s
-**- Voltage of the fuel pump while the engine is stopped and the pump operates (approx. 2 volts less than battery's voltage).
Reading example:
During testing, a voltage of 12.5 volts is measured. Since the pump's voltage is 2 volts less than the battery's, a minimum flow of 540 cc/30 s results.
If the minimum flow is not obtained:
–  Check the fuel hoses for possible kinks or clogging.
  N20-0134
–  Remove the flexible supply hose -1- from the fuel filter intake.
–  Attach pressure tester -V.A.G. 1318- to the flexible hose, using the adapter -V.A.G. 1318/17-.
–  Check the flow again.
If maximum flow is now reached:
–  Renew fuel filter.
If once again the minimum flow is not reached:
–  Remove the fuel supply unit and check whether the filter is dirty.
Only if no fault has been detected to this time:
–  Renew the fuel supply unit.
The fuel flow has been attained, but, in spite of this, there is reason to believe that there is a fault in fuel supply (for instance: a momentary fault in fuel supply):
–  Test the fuel pump's current consumption, proceeding as follows:
–  Reattach the fuel hoses that were removed.
  N20-0242
–  With a current detector, attach the multimeter -V.A.G. 1715- to one of the fuel pump's supply cables (clamp connector's exterior contacts).
–  Start the engine and allow it to idle.
–  Measure the fuel pump's current consumption. Theoretical value: 8 amperes max.
  Note!
If it is a temporary fuel system fault, the test can also be carried out during a road test, in which case, an additional person's help is required.
If the power consumption is surpassed:
–  Fuel pump faulty, renew the fuel supply unit → Chapter; Fuel supply unit: removing and installing.
  N20-0061

Check the fuel pump non-return valve > < Test operation and battery supply