Auxiliary Fuel Pump (V393) (In-Line Electric Fuel Pump), Checking

Auxiliary Fuel Pump (V393) (In-Line Electric Fuel Pump), Checking

Special tools, testers and auxiliary items required

• Fuel Inj. Pressure Gauge-CIS (V.A.G 1318)

Test Conditions:

• Battery voltage at least 12.5 volts.

• Fuel filter OK.

• Fuel tank at least 1/2 full

• Ignition turned off

- Remove the engine cover. Refer to => [ Engine Cover ] Engine Cover.


• Follow the guidelines for a clean working environment when working on the fuel supply system. Refer to => [ Clean Working Conditions ] Fuel Supply.

• Always follow these rules before and during work.

• Before opening the fuel system, lay a clean cloth around the connection point and carefully loosen it, which lowers the pressure.

- Remove the fuel supply line - arrow - from the high pressure pump.






- Connect the fuel inj. pressure gauge-CIS (V.A.G 1318) and the adapter - 2 - to the fuel supply line - 1 -. Connect the other adapter - 3 - to the connection on the high pressure pump.






• The fuel inj. pressure gauge-CIS (V.A.G 1318) is switched on in the fuel supply line.






- Connect the vehicle diagnostic tester and perform the Guided Function "Check electrical fuel pumps".

• The fuel pump now runs for 30 seconds.

- Let the fuel pumps run until the highest fuel pressure is reached.

• Specified value: minimum 3.5 bar

If the specification is not obtained:

Check the connection between the fuel inj. pressure gauge-CIS (V.A.G 1318) and fuel line for leaks.

Check the fuel inj. pressure gauge-CIS (V.A.G 1318) for leaks.

Check the fuel lines and their connections for leaks.

Is the fuel filter clogged?

Check the delivery rate of the transfer fuel pump (G6). Refer to => [ Fuel Delivery, Checking ] Transfer Fuel Pump (G6), Checking.

• Check the fuel system for leaks.