Auxiliary Fuel Pump V393/Fuel Pump 2 V277 (In-Line Fuel Pump)

Auxiliary Fuel Pump V393/Fuel Pump 2 V277 (In-line Fuel Pump)

• Due to a software revision, the component name for the in-line electric fuel pump was changed from "auxiliary fuel pump" to "fuel pump 2". They are the same component.

Special tools, testers and auxiliary items required

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

Test Conditions:

• Battery voltage is at least 12.5 volts

• The fuel filter is OK.

• Fuel tank: Fuel level, min. reserve.

• The ignition is off.

- Remove the engine cover.


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

• Always follow these rules before and during work.

• Place a clean cloth around the connection before opening the system. Remove the hose connection carefully to release the pressure.

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






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






• The fuel inj. pressure gauge - CIS (V.A.G 1318) is turned 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 pump run until the highest fuel pressure is reached.

• Specified value: at least 3.5 bar

If the specified value is not obtained:

Check the connection between the fuel pressure gauge and fuel lines for leaks.

Check the pressure gauge for leaks.

Check the fuel lines and their connections for leaks.

Fuel filter clogged?

Check the delivery rate of the transfer fuel pump. Refer to => [ Fuel Delivery Quantity, Checking, ] Fuel Delivery Quantity, Checking,.

• Check the fuel system for leaks.