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Checking residual pressure > < check operation and electricity supply

Leon Mk2

Checking fuel pressure
Checking fuel pressure
  WARNING
Fuel supply line is 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 release pressure by carefully pulling hose off connection.
   
–  Disconnect the supply line (metal connection) -arrow- and clean escaping fuel with a cloth.
  Note
Press in safety ring to release fuel lines.
  S10-0099
–  Connect the fuel supply pipe to pressure tester -VAS 6550-, using the adapter -VAS 6550/1- and -VAS 6550/2-.
–  Make sure that the drain cock is closed and that the flow valves are open.
–  Control and build up the pressure of the fuel pump using the actuator diagnostic function.
–  Take the fuel pressure reading on the pressure gauge.
l  Specification: 4.0 … 7.0 bar
If the fuel pressure is correct, check the retention pressure → Chapter.
If specification is exceeded:
–  Check that the return pipe between the filter and the fuel pump is not kinked or blocked.
If no fault is found:
–  Pressure limiting valve in the fuel filter faulty: Replace the fuel filter.
If specification is not obtained:
–  Check the fuel pressure before the filter as follows:
  N20-10628
–  Separate the fuel supply hose -arrow- from the fuel filter.
  N20-10629
–  Connect fuel supply line pressure gauge -VAS 6550- using the adapter -VAS 6550/1- and -VAS 6550/2- between the fuel filter and the fuel supply line.
–  Make sure that the drain cock is closed and that the flow valves are open.
–  Start engine and run at idling speed.
  N20-10630
–  Slowly close the shut-off valve on the pressure gauge -A-. The pressure should increase to at least 7.0 bars. Once the 7.0 bar has been reached, open the shut-off valve immediately!
If the pressure has increased:
–  Fuel filter is OK. Pressure limiting valve in the fuel filter faulty: Replace the fuel filter.
If the pressure does not increase:
–  Fuel pump is defective, renew fuel delivery unit → Chapter.
  N20-10598

Checking residual pressure > < check operation and electricity supply