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Mixture preparation system, electronic inj.,Gas > < Inspecting the electronic power control (electronic throttle)

Replacement and Installation of Fuel Supply System Components

Check the flow rate
Check the flow rate
Test conditions
l  Voltage supply o.k.
l  Remote control -V.A.G 1348/3A - connected
Test sequence
–  Remove fuel filler cap from fuel filler neck.
–  Remove the intake manifold cover.
   
–  Open the screwed connection -arrow- and catch the fuel which flows out with a cleaning cloth.
  WARNING
The fuel system is under pressure! Place a clean cleaning cloth around the connection point before detaching hose connections. Reduce pressure by carefully removing the hose.
  N24-0586
–  Connect pressure gauge -V.A.G 1318 - with adapter -V.A.G 1318/12 - to the fuel feed line.
–  Fit hose -V.A.G 1318/1- onto the adapter -V.A.G 1318/11- of the pressure measuring device and hold in a measuring vessel.
–  Open shut-off cock on 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 0.3 MPa overpressure (3 bar). Now do not make any further changes to the position of the shut-off cock.
–  Drain the measuring vessel.
–  The flow rate of the fuel pump is dependent on the battery voltage. Therefore connect the multimeter to the vehicle battery.
–  Activate remote control for 30 seconds while measuring the battery voltage.
  N20-0213
–  Compare the fuel rate with the specified value.
*) Minimum flow rate cm 3/30 seconds
**) Voltage at fuel pump when engine not running and pump operating (approx. 2 volts less than battery voltage).
Read out examples:
During the test a voltage of 12.2 V was measured on the battery. As the voltage on the pump is approximately 2 volts less than the battery voltage, a minimum flow rate of 550 cm 3/30 s is obtained.
If the minimum flow rate is not reached:
–  Check the fuel lines for possible restrictions (kinks) or blocking.
  N20-0098
–  Disconnect feed line -1- from the fuel filter inlet.
–  Connect pressure gauge -V.A.G 1318 - with the adapter -1318/10 - at the hose.
–  Repeat flow rate test.
If the minimum delivery volume now reached:
–  Replace fuel filter.
If the minimum delivery volume is still not reached:
–  Remove fuel delivery unit ( → Chapter) and inspect the filter strainer for soiling.
If you have still not found any fault up to this stage:
–  Fuel pump defective, replace the fuel delivery unit → 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 the power consumption of the fuel pump as follows:
–  Connect all released fuel lines.
–  Remove the boot floor cover.
  N20-0060
–  Connect the multimeter with the current probe onto the green/yellow line (chamber 1 on the four part plug) of the wiring loom.
–  Start engine and run in idle.
–  Measure voltage consumption of the fuel pump. Specified value: a maximum of 8 amps.
  Note
If the fault in the fuel supply system is intermittent then tests can be undertaken during a test drive but then two people are required for this.
If the power consumption is exceeded:
–  Fuel pump defective, replace the fuel delivery unit → Chapter.
  N20-0402

Mixture preparation system, electronic inj.,Gas > < Inspecting the electronic power control (electronic throttle)