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Engine control unit > < Checking injectors for leaks and quantity injected

Golf Mk4

Checking fuel pressure regulator and holding pressure
   
Checking fuel pressure regulator and holding pressure
Special tools and workshop equipment required
t  Pressure tester -V.A.G 1318-
t  Adapter -V.A.G 1318/9-
t  Adapter set -V.A.G 1318/17-

The fuel pressure regulator regulates the fuel pressure depending on intake manifold pressure.
The specification for the check is dependent upon the working pressure of the fuel pump. This is approx. 3.0 bar.
Test prerequisite
l  Fuel pump delivery rate OK, checking → Chapter.
Test procedure
–  Remove fuse no. 28 for fuel pump out of fuse holder.
  WARNING
Fuel system is under pressure! Wear protective glasses and gloves to avoid injuries and skin contact. Before opening the system place a cloth around the connection. Then release pressure by carefully loosening the connection.
   
–  Disconnect the fuel supply pipe coupling -1- (black or black marking) and catch the fuel which escapes with a cloth.
  A10-0140
–  Connect pressure tester -V.A.G 1318- with adapter -V.A.G 1318/9- and adapter set -V.A.G 1318/17- to supply line and fuel rail hose.
–  Open shutoff valve of pressure tester. The handle points in direction of flow.
–  Fit fuse no. 28 for fuel pump in fuse holder.
–  Start engine and run at idling speed.
–  Measure fuel pressure. Specification: approx. 2.5 bar
  N24-0698
–  Pull vacuum hose off fuel pressure regulator -arrow-. Fuel pressure must increase to approx. 3.0 bar.
If the specification is not attained:
–  Check delivery volume of fuel pump → Chapter.
If the specification is obtained:
–  Switch off ignition.
–  Now check for leaks and holding pressure. Do this by observing pressure drop on gauge. After 10 minutes, there must be a residual pressure of at least 2.0 bar.
If holding pressure drops below 2 bar:
–  Start engine and run at idling speed.
When the fuel pump has built-up the pressure again:
  N24-1282
–  Switch ignition off after the pressure has built up. At the same time, close shutoff valve on pressure tester -V.A.G 1318- (lever perpendicular to direction of flow -arrow-).
–  Again watch pressure drop on gauge.
If the pressure does not drop:
–  Check fuel pump non-return valve → Chapter.
If the pressure drops again:
–  Check pressure tester -V.A.G 1318- for leaks.
–  Check line connections, O-rings on fuel rail and injectors for leaks.
If no leaks can be found:
–  Switch off ignition.
–  Renew fuel pressure regulator → Item.
When pressure tester -V.A.G 1318- is removed after test has been completed:
–  Hold a cloth over the adapter to be loosened and remove pressure tester.
  N24-0618

Engine control unit > < Checking injectors for leaks and quantity injected