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Checking intake air preheating > < Checking injectors

Leon Mk1

Checking fuel pressure regulator and holding pressure
Checking fuel pressure regulator and holding pressure
The fuel pressure regulator regulates the fuel pressure depending on intake manifold pressure.
Special tools and workshop equipment required
t  Pressure tester -V.A.G 1318-
t  Adapter -1318/1-
t  Adapter -1318/11-
Test conditions
l  Fuel pump delivery rate has to be OK. Check dilivery rate → Chapter, checking fuel pump.
Test sequence
  Caution
Fuel system is under pressure! Before opening the system place a cloth around the connection. Then release pressure by carefully loosening the connection.
   
–  Pull fuel supply hose (white marking) -1- off connection on fuel rail -2-.
–  Connect pressure gauge -V.A.G 1318- to supply pipe/hose and to hose to fuel rail using adapters -V.A.G 1318-from the fuel supply hose.
–  Open shut-off tap on pressure gauge. (The handle points in through-flow direction -arrow-).
–  Start engine and run at idling speed.
–  Check fuel pressure. Specification: Approx. 2.5 bar
  E24-0159
–  Pull vacuum hose -1- from fuel pressure regulator off -2-. The fuel pressure must increase to 3.0 bar.
–  Switch off ignition
–  Check for leaks and holding pressure by watching pressure drop on gauge. After 10 minutes there must be min. 2 bar.
If the holding pressure drops below 2 bar:
–  Start engine and run at idling speed.
–  When the pressure has built-up again, switch off ignition and at same time close gauge shut-off tap. The shut-off tap handle is at right-angles to through flow direction.
–  Observe pressure drop on gauge.
If the pressure does not drop:
–  Check fuel pump non-return valve → Chapter, Checking fuel pump non-return valve.
If the pressure drops again:
–  Open pressure gauge shut-off tap again.
–  Start engine and run at idling speed.
  N24-0409
–  When the pressure has built-up again, switch off ignition and at same time clamp off return supply hose (with blue markings) -1-.
If the pressure does not drop:
–  Renew fuel pressure regulator → Item.
If the pressure drops again:
–  Check pipe connections, O-rings on fuel rail and injectors for leaks.
–  Check pressure gauge for leaks.
  Note!
Before removing pressure gauge place a cloth around the connections to be loosened.
  N24-0415

Checking intake air preheating > < Checking injectors