Fuel Supply System

Fuel Supply System

=> [ Safety Precautions ]

=> [ Clean Working Conditions ]

=> [ Fuel Pump Electrical, Testing ]

=> [ Fuel Pump Delivery Quantity, Checking ]

For all fuel supply system component locations. Refer to repair information

For all fuel supply system removal/installation procedures and torque specifications. Refer to repair information

Check the Technical Bulletins for information that may supersede any information included in this service information. Refer to repair information.

• All manufacturers special tools as well as common tools may contain a manufacturer specific part number. These tools may be substituted with an equivalent aftermarket tool or are available for purchase through Audi.

• Manufacturers special tools as well as common tools that contain a manufacturer specific part number may be referenced in the test procedure illustrations showing the tool use or installation. If the manufacturer specific tool is not being used, an equivalent aftermarket tool may be installed in the same manner as the manufacturers special tool.

• The manufacturers test box Test Box 105 Pin (VAG1598/31) is available for purchase or rental.

The use of nails, paper clips, or another unauthorized materials to back-probe electrical harness connectors is strictly prohibited and may cause damage to the electrical harness connectors, terminal ends or damage to a component. Use only the manufacturers test lead kit or an equivalent aftermarket test lead kit for back-probing all electrical harness connectors.

Safety Precautions

• Fuel system is under pressure! Before opening system, place rags around the connection area. Then release pressure by carefully loosening the connection.

• Vehicles with FSI engine: The engine section of the fuel system, after the high pressure pump, is under extremely high pressure! When working on engine or fuel injection system, pressure must be relieved to residual pressure before opening high pressure components

Perform the following steps before beginning work on the fuel supply system:

• Disconnect the battery Ground (GND) cable with the ignition switched off. See repair information.

• Open the fuel filler flap briefly and then close again.

When removing and installing components from full or partially full fuel tanks, observe the following:

• The fuel tank must only be partially full. How much fuel can remain in the fuel tank may be read in the respective work description. Empty the fuel tank if necessary.

• Before starting work, switch on the exhaust extraction system and place an extraction hose close to the installation opening of the fuel tank to extract escaping fuel fumes. If no exhaust extraction system is available, a radial fan (as long as motor is not in air flow) with a displacement greater than 15 m3/h can be used.

• Prevent fuel from contacting the skin! Wear fuel-resistant gloves!

Clean Working Conditions

When working on the fuel supply/injection system, pay careful attention to the following rules of cleanliness:

• Thoroughly clean all connections and the surrounding area before disconnecting.

• Place parts that have been removed on a clean surface and cover them. Do not use fluffy cloths!

• Carefully cover over opened components or seal, if repairs are not performed immediately.

• Only install clean components: Only unpack replacement parts immediately prior to installation. Do not use parts that have been stored unpacked (e.g. in tool boxes etc.).

• When the system is open: Do not work with compressed air. Do not move vehicle unless absolutely necessary.

Fuel Pump Electrical, Testing

Special tools, testers and auxiliary items required

• Hand held remote control (jumper).

• Multimeter.

• Electrical connector test lead set.

Test conditions

• Battery voltage 12.5 V.

• Fuse - 29 - in fuse holder at left of instrument panel is OK.

• Fuel filter OK.

• Ignition switched off.

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ General Diagnosis ] General Diagnosis.

Start diagnosis

- Remove the rear seat bench. Refer to repair information.

- Remove cover retainers - arrows - from the right sealing flange.

- Disconnect the electrical harness connector - arrow - from the fuel delivery unit.

- Connect a Hand held remote control (jumper) to terminal - 1 - of the fuel delivery unit and to vehicle battery (+).

- Connect a jumper cable from an Electrical connector test lead set to terminal - 5 - of the fuel delivery unit and to vehicle Ground (GND).

- Press switch on the Hand held remote control (jumper).

• The Fuel Pump (FP) runs quietly. Avoid surrounding noises while testing the fuel pump.

- Listen for an operating noise from the fuel pump.

If no operating noise is heard:

- Remove the fuel delivery unit.

- Using a Multimeter, check the electrical circuit between terminals - 1 - and - 5 - of the fuel delivery unit for continuity.

Specified value: 0 ohms.

If a malfunction is detected in the electrical circuit:

- Check the electrical harness connector for damage, corrosion, lose or broken terminals.

- Repair the electrical circuit.

If no malfunction is detected in electrical circuit, replace the fuel pump.

- Install the fuel delivery unit.

Fuel Pump Delivery Quantity, Checking

Special tools, testers and auxiliary items required

• Hand held remote control (jumper).

• Multimeter.

• Electrical connector test lead set.

• Fuel pressure test set (high pressure).

• Measuring container, fuel-resistant.

Test conditions

• Battery voltage 12.5 V

• Fuel filter OK

• Fuel tank at least 1/4 filled.

• Fuel pressure regulator OK. Refer to repair information.

• Ignition switched off.

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ General Diagnosis ] General Diagnosis.

Start diagnosis

- Remove the fuel filler cap from fuel filler t3.2 V6 4V Engine Mechanical, Engine Code(s): BUB.

- Remove rear seat bench. Refer to repair information.

- Remove cover retainers - arrows - from the right sealing flange.

- Disconnect the electrical harness connector - arrow - from the fuel delivery unit.

Fuel system is under pressure! Before opening the system, place rags around the connection area. Then release the pressure by carefully loosening the connection.

- Disconnect fuel line - arrow - by pulling release button.

- Connect the Fuel pressure test set (high pressure) onto the disconnected fuel supply line.

- Connect an assisting hose - arrow - on to the Fuel pressure test set (high pressure) and hold it into a measuring container.

- Open the shut-off valve of pressure gauge. The lever points in direction of flow.

- Generate pressure in the fuel system by pressing the remote control switch and slowly closing the pressure gauge shut-off valve.

• Specification: 4 bar positive pressure.

- From this point on do not move position of shut-off valve.

- Empty the measuring container.

- Press switch on remote control for 15 seconds.

- Compare quantity of fuel delivered with minimum delivery rate in the diagram (cm3/15s).

• Voltage at the fuel pump with engine stopped and fuel pump running is approx. 2 volts less than battery voltage.

If minimum delivery quantity is not obtained, the following malfunctions may be present:

• Fuel lines pinched.

• Fuel filter clogged.

• Fuel pump faulty.

Assembly is performed in reverse order of removal. Note the following:

- Install the rear seat bench. Refer to repair information.