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Leon Mk1

Fuel pressure regulator and retention pressure: check
Fuel pressure regulator and retention pressure: check
The fuel pressure regulator regulates the fuel pressure depending on the intake manifold pressure.
   
Special tools and workshop equipment required
t  Manometer -V.A.G 1318-
t  Adapter -V.A.G 1318/9-
t  Adapter -V.A.G 1318/17-

Testing conditions
l  The flow of the fuel pump should be correct; check the flow → Chapter, Fuel pump: check.
Testing process
  Caution
The fuel system is under pressure. Before opening the system, place a cloth around the point of the connection. Next, eliminate the pressure carefully separating the connection.
   
–  Remove the fuel supply hose (with a white mark) from the supply pipe.
–  Connect the pressure measurer -V.A.G 1318- to the hose using the adapter -V.A.G 1318/17- and to the supply pipe using the adapters /9 and /17.
–  Open the valve of the pressure measurer. The lever indicates the flow direction.
–  Start the engine running at idling speed.
–  Measure the fuel pressure.
   Theoretical value: 2.5 bar
  N24-0698
–  Remove flexible vacuum tube from fuel pressure regulator -1- on the intake manifold side -2-. Fuel pressure should increase by approximately 3.0 bar.
–  Turn off the ignition.
–  Check the tightness and retention pressure noting the pressure drop on the manometer. After 10 minutes, there should be a minimum pressure of 2 bar.
If the retention pressure drops below 2 bar:
–  Start the engine running at idling speed.
  N24-0315
–  As soon as the pressure has been created, turn off the ignition, closing manometer -V.A.G 1318- valve at the same time (lever in transversal position to flow direction -arrow-).
–  Note the pressure drop on the manometer.
If the pressure does not drop:
–  Check the fuel pump retention valve → Chapter
If the pressure drops again:
  N24-0618
–  Open the pressure measurer -V.A.G 1318- valve (lever in flow direction).
–  Start the engine running at idling speed.
–  As soon as the pressure has been created, turn off the ignition strangulating the return hose (with a blue mark) at the same time.
If the pressure does not drop:
–  Renew the fuel pressure regulator → Item.
If the pressure drops again:
–  Check the tightness of the connections of tubes, O-rings of the fuel distributor and injectors.
–  Check the tightness of the manometer.
  Note!
Before removing the manometer, place cloths around the point of connection.
  N24-0698

Checking components > < Servicing injection system