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Checking for injectors sticking open > < Checking return flow rate of injectors with engine running

A3 Mk2

Checking return flow rate of injectors at starter cranking speed
Checking return flow rate of injectors at starter cranking speed
If it is not possible to start engine, check return flow rate of injectors at starter cranking speed.
Special tools and workshop equipment required
   
t  Injection rate comparison meter -V.A.G 1348/2 B-
t  4 lengths of hose (made up in the workshop) to fit return line connections on injectors
  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.
Each injector normally has a relatively low return flow rate. If the return flow rate at one injector is relatively high compared to the other injectors, that injector is probably defective.
–  Remove engine cover panel → Chapter.
–  Remove noise insulation from injectors.
–  Clean all return line connections (with commercial cleaning solution or similar) before removing.
–  Dry all components after cleaning.
  W00-0614
–  Pull return line connections off injectors; to do so, press both tabs down and at the same time pull release pin upwards -arrow-.
  Note
No dirt must be allowed to get into the disconnected return lines or the open connections on the injectors.
  N15-10404
–  Detach electrical connector -5- from fuel pressure regulating valve -N276-.
  Note
This prevents fuel from being injected when starter is operated.
–  Connect the 4 hoses onto return line connections of all 4 injectors.
–  Run the 4 hoses into injection rate comparison meter -V.A.G 1348/2 B-.
–  Operate starter three times. (Wait approx. 20 seconds each time after operating starter to prevent it from overheating.)
l  Specification of return flow rate: 0 ml
–  If fuel comes out of one injector, that injector must be renewed.
–  Re-attach electrical connector on fuel pressure regulating valve -N276-.
Installing fuel return lines
–  Renew O-rings for all return line connections.
  Note
Lubricate all O-rings with engine oil or assembly oil before installing.
–  Push the return line connections carefully over the new seals and onto the injectors. The catch should engage audibly. Then press release pin down carefully.
–  Check fuel system for leaks → Chapter.
–  Erase entry in event memory using a diagnostic tester.
  N23-10226

Checking for injectors sticking open > < Checking return flow rate of injectors with engine running