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Rules for cleanliness > < Safety precautions when working on fuel supply system

Golf Mk5

Releasing fuel pressure in high-pressure section
Releasing fuel pressure in high-pressure section
  WARNING
The injection system consists of a high-pressure section (maximum approx. 120 bar) and a low-pressure section (approx. 6 bar).
Prior to opening the high-pressure area, e.g. when removing the high-pressure pump, fuel rail, injectors, a fuel line, or the fuel pressure sender -G247-, the fuel pressure in the high-pressure area must be reduced to a residual pressure of approx. 6 bar. The appropriate procedure is described as follows.
   
–  Pull electrical connector off fuel pressure regulating valve -N276--arrow-.
–  Run engine at idling speed for approx. 10 seconds.
  Note
t  When the engine is idling and the electrical connector is pulled off the fuel pressure regulating valve -N276- the pressure in the high-pressure area will drop to approx. 6 bar.
t  When the high-pressure is reduced, the high-pressure system must be opened, because the fuel pressure can rise by warming up.
–  Switch off ignition.
  WARNING
The fuel system is pressurised!
t  Wear eye protection and protective clothing to avoid possible injury and skin contact.
t  Before loosening line connections, wrap a cloth around the connection. Then release pressure by carefully pulling off line.
–  Wrap a clean cloth around the connection and carefully open to release residual pressure of approx. 6 bar. Catch the escaping fuel.
–  After completing work, read fault memory of engine control unit, erase all fault entries that have been created by pulling off connector.
  Note
If the fault memory was cleared, the readiness code must be generated → Vehicle diagnostic tester„Guided functions“.
  N20-10282

Rules for cleanliness > < Safety precautions when working on fuel supply system