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

Leon Mk1

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 hole plug.
  Caution
The fuel system is under pressure. Before opening the system, place a cloth round the connection. Then, eliminate the pressure loosening the connection carefully.
   
–  Remove the supply line -1- and wipe up any spilt fuel.
  E10-0018
–  Connect pressure gauge -V.A.G 1318- to the fuel supply line with adaptors -V.A.G 1318/17- and -V.A.G 1318/23-.
–  Attach hose -V.A.G 1318/1- to adaptor -V.A.G 1318/11- of the pressure gauge and fit the end in a measuring glass.
–  Open the shut-off valve of the pressure gauge. The lever points in the direction of flow -A-.
–  Activate the remote control -V.A.G 1348/3 A- and slowly close the shut-off valve until the pressure gauge shows a pressure of 3 bar. From this moment on, do not change the position of the shut-off valve.
–  Drain the measuring glass.
–  The fuel pump flow depends on battery voltage. Thus, connect the multimeter to the battery of the vehicle with the auxiliary leads of -V.A.G 1594-.
–  Activate the remote control for 30 seconds, measuring the battery voltage.
  E20-0014
–  Compare the flow reading with the target value.
* Minimum flow cm3/30 s.
** Voltage at the fuel pump when the engine is stopped and the pump running (approx. 2 volts less than battery).
Example reading:
During the test, the voltage measured at the battery was 12.5 volts. Given that at the pump there are about 2 volts less than at the battery the resulting minimum supply flow is 200 cc/30 s.
If the minimum flow is not reached:
–  Check the fuel lines for possible crimps or clogs.
–  Remove the supply hose at the entrance to the fuel filter.
  N20-0189
–  Attach to the supply hose the pressure gauge -V.A.G 1318- with adaptor/17.
–  Test the flow again.
If the minimum flow is now reached:
–  Replace the fuel filter.
If the minimum flow is still not reached:
–  Remove the fuel supply unit and check the filter for dirt.
Only if no fault has been found until now:
–  Replace the fuel supply unit.
If the fuel flow has been reached, but, despite this, there seems to be a fault in the fuel supply (e.g. a momentary failure in fuel supply):
–  Measure the voltage consumption of the fuel pump, as follows:
–  Reattach the fuel lines that were removed.
  N20-0242
–  With the 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 run it at idling revs.
–  Measure the voltage 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.
If the voltage consumption is exceeded:
–  Fuel pump faulty, replace the fuel supply unit → Chapter.
  N20-0061

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