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Activated charcoal filter system: > < Overview: fuel tank and fuel filter with components

Leon Mk1

Fuel delivery quantity: Check
Fuel delivery quantity: Check
Special tools and workshop equipment required
t  Step ladder
l  Power supply is okay
l  Fuel pressure controller and retaining pressure okay.
l  Fuel filter OK.
–  Remove filler cap from fuel tank filler neck.
   
–  Using the auxiliary cables of the auxiliary measuring set -VAG 1594C-, connect the remote control -V.A.G 1348/3A- to contact -1- of the fuel pump and to the positive terminal of the battery
–  Using the auxiliary cables of the auxiliary measuring set -VAG 1594C-, connect the contact -5- of the plug connector to the contact -5- of the fuel pump.
  Note
The delivery rate of the fuel pump is measured at a pressure of 4 bar. This is why you have to check the fuel pressure before measuring the delivery rate.
  WARNING
Fuel system is under pressure! Wear safety goggles and appropriate clothing to avoid injury and contact with skin. Before loosening hose connections, wrap a cloth around the connection. Then eliminate the pressure by carefully separating the pipe.
  E20-10074
–  Remove return line -1- of the fuel pressure regulator.
  Note
Press in safety ring to release fuel lines.
–  Connect the Adapter -VAG 1318/17A- to the fuel pressure regulator and place the adaptor end in a measuring container.
–  Operate the remote control -VAG 1348/3A- for 5 seconds to fill the fuel filter.
–  Empty the measuring container.
–  The quantity of fuel delivered by the fuel pump is dependent upon voltage. Therefore connect multimeter to the battery.
–  Operate remote control for 30 seconds and measure battery voltage.
  N20-0526
–  Compare the fuel flow measured with the specification.
*) Minimum delivery rate cm3/30 s
**) Voltage on the fuel pump when the engine is stationary and with running pump (approx. 2 volt under battery voltage).
Readout example:
During the test, the battery voltage is measured at 12.5 volts. As the voltage at the pump is approx. 2 V less than the battery voltage, this will equate to a minimum delivery of 600 cm3/30 s.
If the minimum delivery rate is not attained:
–  Check the fuel supply pipes to the filter for possible restrictions (kinks) or blockages.
If the fuel line is not damaged:
–  Check the flow of fuel before the filter.
  WARNING
Fuel supply pipes are pressurised. Wear safety goggles and appropriate clothing to avoid injury and contact with skin. Before loosening hose connections, wrap a cloth around the connection. Then eliminate the pressure by carefully separating the pipe.
  N20-10138
–  Pull the supply hose -1- from the fuel filter inlet.
  Note
Press in safety ring to release fuel lines.
–  Connect the pressure tester -VAG 1318- using adapter unit -V.A.G 1318/17A- as shown.
–  Connect the adaptor -V.A.G 1318/1- to the adaptor -V.A.G 1318/11- of pressure gauge and place it into a measuring container.
–  Open cut-off tap on pressure gauge. The lever then points in through flow direction -A-.
–  Operate the remote control -VAG 1348/3A-. In doing so, slowly close the cut-off tap until 4 bar is shown on the manometer. From here on, do not change position of shut-off tap.
–  Empty the measuring container.
–  Activate remote control again for 30 seconds. Compare the flow with the first value measured.
If the minimum delivery rate is now attained:
–  Replace fuel filter
If the minimum delivery rate is again not attained:
–  Remove the fuel delivery unit and check the strainer filter for soiling.
Only when up to now no fault has been detected:
–  Replace fuel delivery unit → Chapter.
–  Reconnect all disconnected fuel pipes.
–  Purge the fuel system → Chapter.
If delivery quantity has been attained, but nevertheless you suspect a fuel supply system fault (e.g. intermittent failure of fuel supply system):
–  Checking current consumption of fuel pump → Chapter.
  N20-0531

Activated charcoal filter system: > < Overview: fuel tank and fuel filter with components