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Checking intake air system for leaks (unmetered air) > < Checking engine speed sender

Golf Mk3

Motronic injection and ignition system (6-Cyl. engine)
Checking components
Checking fuel pressure regulator and holding pressure

The fuel pressure regulator controls the fuel pressure dependent upon intake manifold pressure.

Special tools, testers, measuring instruments and auxiliary items required

  • ◆ Pressure tester V.A.G 1318
  • ◆ Adapter 1318/1

Test conditions

  • ● Fuel pump delivery rate OK, checking:

=> Rep. Gr. 20; Removing and installing parts of fuel system; checking fuel pump

Test sequence

Warning!
The fuel system is pressurized! Before loosening hose connections or opening the test connection, wrap a cloth around the connection. Then release pressure by carefully pulling off the hose or carefully unscrewing sealing plug.

The specifications for this test are dependent on fuel pump working pressures.
     ä 07.95 approx. 4 bar
     08.95 ▸ approx. 3 bar
 
N24-0013
  • ‒ → Unscrew drain plug -1- out of test connection at fuel rail.
  • ‒ Connect pressure gauge V.A.G 1318 with adapter V.A.G 1318/10 and hose V.A.G 1318/1 to test connection.
  • ‒ Close the pressure gauge cut-off tap. The lever points 90° to throughflow direction -arrow-).
  • ‒ Start the engine and run at idling speed.
  • ‒ Check fuel pressure.
         Specification:
         ▸07.95 approx. 3.5 bar
         08.95 ▸ approx. 2.5 bar
 
N24-0125
  • ‒ → Pull vacuum hose off fuel pressure regulator on intake manifold upper part -arrow-. The fuel pressure must increase to
         ä 07.95 approx. 4 bar
         08.95 ▸ approx. 3 bar
  • ‒ Switch off ignition.
  • ‒ Check for leaks and holding pressure by observing pressure drop on gauge. After 10 minutes the pressure must be at least
         ▸07.95 approx. 2.5 bar
         08.95 ▸ approx. 2.0 bar

If the pressure drops:

  • ‒ Start the engine and run at idling speed.
  • ‒ After pressure has built-up switch off ignition. Clamp-off the return hose -with blue markings- on fuel rail at the same time.
  • ‒ Observe pressure drop on gauge.

If the pressure does not drop:

  • ‒ Renew fuel pressure regulator

If the pressure drops again:

  • ‒ Check fuel pump non-return valve.

=> Rep. Gr. 20; Removing and installing parts of fuel system; checking fuel pump

  • ‒ Check pipe connections, O-rings on intake manifold lower part and injectors for leaks.
  • ‒ Check pressure gauge for leaks.

Note:

Before removing pressure gauge place a cloth around the connections to be loosened.

Checking intake air system for leaks (unmetered air) > < Checking engine speed sender