Fuel Injector, Checking

Fuel Injector, Checking

Special tools, testers and auxiliary items required

• Remote Control (V.A.G 1348/3A)

• Adapter Cable (V.A.G 1348/3-2)

• Injector Rate Tester (V.A.G 1602)

• Connector Test Set (V.A.G 1594 C)

• Test Instrument Adapter/DSO (5-pin) (VAS 5565)

Checking for Leaks

• The fuel pressure must be OK.

- Remove the fuel rail - 2 - with the fuel injectors installed. Refer to => [ Fuel Injectors ] Fuel Injectors and place it on a clean cloth.






Do not disconnect the battery and do not disconnect the fuel supply line at the quick acting coupling or at the fuel rail.

• The connectors must be disconnected from the fuel injectors.

- Remove the rear seat bench.

- Remove the cover from the fuel delivery unit.






- First, pull on the connector - arrow - without pressing the retainer to make sure it is connected securely. If the connector was not connected correctly, it could cause a fault.






- Disconnect the connector.

- Check the contacts on the connector and the fuel delivery unit for damage.

- Install the test instrument adapter/DSO (5-pin) (VAS 5565) between the connectors on the fuel delivery unit and cover.






- Connect the remote control (V.A.G 1348/3A) to the test instrument adapter/DSO (5-pin) (VAS 5565) and to battery positive (+).

• This step allows the fuel pump to run when the engine is not running.

- Operate the remote control (V.A.G 1348/3A) and look for leaks in the fuel injectors. Only 1 to 2 drops per minute may emit from each injector when the fuel pump is running.

If the fuel loss is greater:

- Disconnect the connection to battery positive (+) and replace the leaking fuel injector. Refer to => [ Fuel Injectors ] Fuel Injectors.

Checking the Injection Quantity

• The fuel pressure must be OK.

• The fuel rail is removed.

• The fuel injectors are installed in the fuel rail and the fuel line connected.

• The remote control (V.A.G 1348/3A) is connected to the fuel delivery unit.

- Place a fuel injector to be tested into a graduated measuring glass from the injector rate tester (V.A.G 1602).

- Using an adapter cable from the connector test set (V.A.G 1594 C) , connect the cable to a terminal on the fuel injector to be checked and to engine ground (-).






- Using adapter cable (V.A.G 1348/3-2) , connect it to the second terminal of the fuel injector and to the remote control (V.A.G 1348/3 A).

- Connect the alligator clip to battery positive (B+).

- Operate the remote control (V.A.G 1348/3A) for 30 seconds.

- Repeat the check on the other injectors. Use new graduated measuring glasses for this.

- After all the fuel injectors have been activated, place the graduated measuring glasses on a level surface and compare the quantity of injected fuel.

Specified value: 85 to 105 ml per injector

While checking the injection quantity, the spray pattern should also be checked. The spray pattern must be the same for all the fuel injectors.

If the measured value of one or more fuel injectors is below or above the indicated specified value:

- Replace the faulty fuel injector. Refer to => [ Fuel Injectors ] Fuel Injectors.