Fuel Injectors, Checking for Leaks and Injection Quantity

Fuel Injectors, Checking for Leaks and Injection Quantity

• Observe safety precautions. Refer to => [ Safety Precautions ] Multiport Fuel Injection.

• Observe the rules for cleanliness. Refer to => [ Clean Working Conditions ] Multiport Fuel Injection.

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 1594C)

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

Checking for Leaks

• Fuel pressure must be OK, checking, refer to => [ Fuel Pressure Regulator and Residual Pressure, Checking ] Testing and Inspection.

- Remove the fuel rail - 2 - with fuel injectors installed. Refer to => [ Fuel Injectors ] Service and Repair 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 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.

- Connect the (VAS 5565) to the connector on the cover and on the fuel delivery unit.





- Connect the (V.A.G 1348/3A) to the (VAS 5565) and to the battery positive (+).

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

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

If the fuel loss is greater:

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

Checking the Injection Quantity

• Fuel pressure must be OK, checking, refer to => [ Fuel Pressure Regulator and Residual Pressure, Checking ] Testing and Inspection.

• Fuel rail removed.

• Fuel injectors installed in fuel rail and fuel line connected.

• The (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 (V.A.G 1602).

- Using adapter cables from (V.A.G 1594C), connect one terminal of the fuel injector to be checked to engine Ground (GND).





- Connect second terminal of the fuel injector with an adapter cable to the (V.A.G 1348/3 A) using (V.A.G 1348/3-2).

- Connect alligator clip to B+.

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

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

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

Specified value: 85 to 105 ml per valve

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

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

- Replace faulty fuel injector. Refer to => [ Fuel Injectors ] Service and Repair.