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Test the fuel pump retaining valve > < Test functioning and voltage supply

Leon Mk2

Test the fuel flow
Test the fuel flow
Test conditions
l  Voltage supply, OK.
l  Remote control -V.A.G 1348/3A-, connected.
Test process
–  Remove the fuel filler cap.
   
–  Detach the supply line -1- and wipe up spilt fuel with a cloth.
  Note!
To do so press the lock buttons on the hose connections.
  Caution
The fuel supply line is under pressure. Before loosening the hose connections, place a cloth around the connection. Then eliminate the pressure by carefully removing the hose.
  E10-0018
–  Connect pressure gauge -V.A.G 1318- to the fuel supply line with adaptor -V.A.G 1318/23- and -V.A.G 1318/17-.
–  Connect hose -V.A.G 1318/1- to pressure gauge adaptor -V.A.G 1318/11- and put the end in a measuring glass.
–  Open the flow valve of the pressure gauge. The lever points in the direction of flow -A-.
–  Operate remote control -V.A.G 1348/3A-, slowly closing the flow valve until the pressure gauge shows a pressure of 3 bar From this moment, do not change the position of the flow valve.
–  Empty the measuring glass.
–  Fuel pump flow depends on battery voltage. Thus the pressure gauge must be connected to the vehicle battery with auxiliary leads -V.A.G 1594A- or -V.A.G 1594C-.
–  Operate the remote control for 30 seconds, measuring battery voltage.
  E20-0030
–  Compare the fuel flow with the target value:
*) Minimum flow cm3/30 s
*) Fuel pump voltage with the engine off and the pump running (approx. 2 volts less than battery voltage)
Example reading:
During the test 12.2 volts battery voltage is measured. Since voltage at the pump is about 2 volts less than at the battery, the resulting minimum flow is 540 cm3/30 s.
If the minimum flow is not reached:
–  Check the fuel lines for crimps and clogs.
  N20-0134
–  Detach the supply line -1- from the entrance to the fuel filter.
–  Connect pressure gauge -V.A.G 1318- to the hose with adaptor -V.A.G 1318/10-.
–  Recheck the flow.
If the minimum flow is reached now:
–  Replace the fuel filter.
If the minimum flow is still not reached:
–  Remove fuel supply unit ( → Chapter) uand check the filter for dirt.
Only if up to this point no fault has been found:
–  Fuel pump faulty, replace the fuel supply unit → Chapter; Fuel supply unit: removing and fitting.
If fuel flow has been reached, but there is still reason to believe that fuel flow is faulty (e.g.: a momentary failure in fuel supply):
–  Test fuel pump current consumption, as follows:
–  Reattach the detached fuel lines.
  E20-0074
–  With a current detector, attach multimeter -V.A.G 1715- to one of the supply wires of the fuel pump (outer contacts of the flange connector).
–  Start the engine and let it idle.
–  Measure the current consumption of the fuel pump. Target value: 8 amperes max.
  Note!
In the event of a momentary fault in the fuel system, the test can also be done during a road test, in which case a second mechanic is needed.
Take the necessary precautions during road tests → Chapter.
If the current consumption is exceeded:
–  Fuel pump faulty, replace the fuel supply unit → Chapter; Fuel supply unit: removing and fitting.
  E20-0075

Test the fuel pump retaining valve > < Test functioning and voltage supply