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

A4 Mk3

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
  Caution
Risk of malfunctions caused by dirt.
Observe → Chapter „Rules for cleanliness and instructions for working on 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.
–  Pull off engine cover panel → Chapter.
–  Clean all return line connections (e.g. with commercial cleaning solution etc.) before removing.
–  Dry all components after cleaning.
  W00-0614
–  Pull return line connections off injectors; to do so, press tabs -1- and -2- 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.
  A23-10455
–  Unplug electrical connector -arrow- at 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
–  Push return line connections carefully onto injectors. The catch should engage audibly. Then press release pin down carefully.
–  Check fuel system for leaks → Chapter.
–  Erase entry in event memory using → Vehicle diagnostic tester.
  A23-10406

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