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Checking residual pressure > < check operation and electricity supply

Leon Mk2

Checking fuel pressure
Checking fuel pressure
  Note
The fuel pressure regulator is installed on the fuel filter.
Checking sequence
  WARNING
The fuel line is under pressure!
Risk of injury to eyes and skin from fuel.
Use protective goggles and clothing to prevent injuries and contact with the skin. Before releasing the connections on the hoses, place absorbent cloths round the connection. Then release pressure by carefully loosening the connection.
   
–  Separate fuel supply pipe coupling -1- and catch escaping fuel with a cleaning cloth.
  Note
Press in safety ring to release fuel lines.
  N10-10528
–  Connect pressure tester -VAS 6550- to fuel supply line with adapter -VAS 6550/1- and -VAS 6550/2-.
–  Make sure that drain tap is closed and cut-off taps are open.
–  Start engine and run at idling speed.
–  Measure fuel pressure.
Specification: 3.90…4.20 bar
If fuel pressure is OK, check holding pressure → Chapter.
If the 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 fuel filter is defective. Renew fuel filter.
If specification is not obtained:
–  Check the fuel pressure before the fuel filter. Proceed as follows for this purpose:
  N20-10628
–  Pull fuel supply line -arrow- off fuel filter.
  N20-10629
–  Connect pressure tester -VAS 6550- between fuel filter and fuel supply line with adapter -VAS 6550/1- and -VAS 6550/2-.
–  Make sure that drain tap is closed and cut-off taps are open.
–  Start engine and run at idling speed.
  N20-10630
–  Slowly close cut-off tap -A-. Pressure must rise to min. 6.0 bar. When 6.0 bar is reached, open shut-off tap again immediately.
If pressure has risen:
–  Fuel filter is OK. Pressure limiting valve in fuel filter is defective. Renew fuel filter → Chapter.
If pressure does not rise:
–  Fuel pump is defective, renew fuel delivery unit → Chapter.
  N20-10598

Checking residual pressure > < check operation and electricity supply