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Check fuel system for leaks > < Checking injectors with vacuum

Leon Mk2

Check pressure retention valve in fuel return line
Check pressure retention valve in fuel return line
The pressure retention valve maintains a residual pressure of approx. 1 bar in the return lines.
This residual pressure is required for the control function of the injectors.
Consult the equivalence table for tools and equipment according to applicability among Seat / VW / Audi / Skoda → Chapter.
Special tools and workshop equipment required
   
t  Tester -VAS 6330-, see equivalent → Anchor
t  Adapter -VAS 6330/3 1-, see equivalent → Anchor
t  Adapter -VAS 6330/3 2-, see equivalent → Anchor
  WARNING
t  Always read rules for cleanliness and instructions for working on fuel system → Chapter.
t  Follow these instructions and rules for cleanliness before starting work and while working on the fuel system.
  W00-10775
–  Loosen the engine cover at the locations -arrows- and remove.
–  Clean return line connection on cylinder 1 (e.g. with cold cleaner) before removing.
–  Dry return line connection on No. 1 cylinder.
–  Cover return line connection on No. 1 cylinder with a cleaning cloth.
–  Separate the connection of the return run line from cylinder 1; remove the retaining clips for this purpose.
  Note
t  Open the return line connection with a narrow screwdriver and long-nosed pliers.
  E10-10087
t  Adhere strictly to rules of cleanliness. No dirt must be allowed to enter the removed fuel return lines or into the open connections on the injector units.
t  Always renew clips.
  N23-10374
–  Mount the fuel return line tester -VAS 6330- with the adapter -VAS 6330/3 1- and the adapter -VAS 6330/3 2- between the return line connection on the injector and the return line.
–  Start engine.
–  Check pressure on pressure gauge.
t  Specification: approx. 1.0 bar
If the specification is not reached, replace the pressure retention valve.
After any work on the fuel system
l  Observe instructions for working on fuel system → Chapter
  N23-10304

Check fuel system for leaks > < Checking injectors with vacuum