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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 protective clothing to avoid possible injury and skin contact. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection.
   
–  Pull off supply line (metal coupling) -arrow- and catch escaping fuel with a cloth.
  Note
Press in safety ring to release fuel lines.
  S10-0099
–  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.
–  Actuate fuel pump with final control diagnosis to build up fuel pressure.
–  Read fuel pressure on pressure gauge.
l  Specification: 4.0 ... 7.0 bar
If fuel pressure is OK, check holding pressure → Chapter.
If the specification is exceeded:
–  Check return line between fuel filter and fuel pump for kinks and blockages.
If no fault is found:
–  Pressure limit valve in fuel filter is defective. Renew fuel filter.
If specification is not obtained:
–  Check fuel pressure upstream of fuel filter; proceed as follows:
  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.
–  Actuate fuel pump with final control diagnosis to build up fuel pressure.
  N20-10630
–  Slowly close cut-off tap -A-. Pressure must rise to min. 7.0 bar. When 7.0 bar is reached, open shut-off tap again immediately.
If pressure has risen:
–  Fuel filter is OK. Pressure limit valve in fuel filter is defective. Renew fuel filter.
If pressure does not rise:
–  Fuel pump defective, renew fuel delivery unit → Chapter.
  N20-10598

Checking residual pressure > < check operation and electricity supply