Fuel Pump Delivery Quantity, Checking

Special tools and workshop equipment required

Switched remote control (jumper).
Multimeter.
Electrical connector test lead set.
Fuel pressure test set.
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.
Ignition switched OFF.

Test procedure

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK .

Start diagnosis

-- Remove the fuel filler cap from fuel filler tube.

-- Remove rear seat bench. Refer to appropriate Service Information.

-- Remove the floor sealing cover.

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

Fig 1: Identifying Fuel Delivery Unit Connector

GWWA20-1067

Courtesy of AUDI OF AMERICA, LLC

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

-- Connect a jumper wire from terminal -4- of the fuel delivery unit to vehicle Ground (GND).

Fig 2: A Jumper Cable From A Electrical Connector Test Lead Set Connected To Terminal Of Fuel Delivery Unit And To Vehicle Ground

GWWA20-1120

Courtesy of AUDI OF AMERICA, LLC

WARNING:

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

-- Disconnect the fuel return line -arrow- by pressing release buttons.

Fig 3: Disconnecting Fuel Return Line By Pressing Release Buttons

GWWA20-1212

Courtesy of AUDI OF AMERICA, LLC

-- Connect a fuel line from the fuel pressure test set to the disconnected fuel return line and hold it in the measuring container.

Fig 4: Connecting Fuel Line From High Pressure Fuel Gauge To Disconnected Fuel Return Line And Hold It In Measuring Container

GWWA20-1096

Courtesy of AUDI OF AMERICA, LLC

-- Press the switch on the remote control (jumper) and operate the fuel pump for 15 seconds.

-- Compare quantity of fuel delivered with minimum delivery rate in the diagram (cm³ /30 sec.).

Fig 5: Fuel Quantity Graph

GWWN20-10138

Courtesy of AUDI OF AMERICA, LLC

NOTE:

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 plugged.
Fuel pump faulty.

-- If necessary, repair any pinched or plugged lines.

If the filter is restricted;

-- Replace the fuel filter. Refer to appropriate Service Information.

If the fuel pump is faulty;

-- Replace the fuel pump. Refer to appropriate Service Information.

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

-- Install the rear seat bench. Refer to appropriate Service Information.

Final procedures

-- Reinstall the engine cover with air filter, if necessary. Refer to the appropriate Service Information.

-- After the repair work, the following work steps must be performed in the following sequence:

Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .