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Checking fuel pressure regulator > < Checking injectors

Polo Mk4

Checking fuel pressure regulator and holding pressure
Checking fuel pressure regulator and holding pressure
  Note
t  The fuel pressure regulator regulates the fuel pressure to approx. 3 bar.
t  The fuel pressure regulator is located on the fuel filter.
   
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-
t  Connector -V.A.G 1318/23-
t  Injection rate comparison meter -V.A.G 1348-

Test procedure
–  Remove fuse holder cover.
   
–  Remove fuse No. 41 (fuel pump) from fuse holder.
  WARNING
Fuel system is under pressure! Wear protective glasses and clothing to avoid injuries and skin contact. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection.
  N24-1481
–  Separate connection for fuel supply line -arrow- and catch escaping fuel with a cloth.
  Note
Press in safety ring to release fuel line.
  S10-0099
–  Connect pressure tester -V.A.G 1318- using adapter -V.A.G 1318/9- and adapter set -V.A.G 1318/17- as shown.
–  Open the pressure tester shut-off tap. The handle points in direction of flow.
–  Refit fuse 41 (fuel pump) in fuse holder.
–  Start engine and run at idling speed.
–  Measure fuel pressure. Specification: approx. 3.0 bar.
If the specification is not obtained
–  Switch off ignition.
–  Check that the fuel pump can create and retain this pressure → Chapter.
–  Check fuel pressure regulator → Chapter.
If the specification is obtained:
–  Switch off ignition.
–  Now check for leaks and holding pressure (entire system). Do this by observing pressure drop on gauge. After 10 minutes, there must be a residual pressure of at least 2.0 bar.
If the holding pressure drops below 2 bar
–  Start engine and run at idling speed.
  N24-1470
–  Switch ignition off after the pressure has built up. At the same time, close shut-off tap on pressure tester -V.A.G 1318- (handle perpendicular to direction of flow) -arrow-.
–  Watch engine-side pressure drop on pressure gauge.
If the pressure drops again:
–  Check pipe connections, injectors, and O-rings on fuel rail for leaks.
–  Check pressure gauge for leaks.
  Note
Before removing pressure tester, place a cloth around the connections to be loosened.
If the pressure does not drop:
–  Check fuel pump non-return valve → Chapter.
–  Check fuel pressure regulator → Chapter.
  N24-0618

Checking fuel pressure regulator > < Checking injectors