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 is at least 1/2 full

• Ignition is 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.

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






- Connect the fuel inj. pressure gauge-CIS (V.A.G 1318) and the hose - 2 - to the fuel supply line - 1 -. Connect the other hose - 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 Electric 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. Refer to => [ Fuel Delivery, Checking ] Transfer Fuel Pump G6, Checking.

• Check the fuel system for leaks.