Transfer Fuel Pump -G6-, CHECKING

Special tools and workshop equipment required 

• Pressure Tester Kit:VAS 6550  with Pressure Tester Kit - Hose 2:VAS 6550/2 
  Fig 1: Identifying Pressure Tester Kit VAS 6550

  Courtesy of AUDI
• Pressure Tester Kit - Regulator Valve:VAS 6550/4 
  Fig 2: Identifying Pressure Regulator Valve VAS 6550/4

  Courtesy of AUDI
• Vehicle Diagnostic Tester
• Fuel-Resistant Measuring Container

A -  Checking Fuel Delivery Rate

-- Observe all test conditions. Refer to TEST CONDITIONS .

-- Open the fuel filler door.

-- Remove the fuel filler neck cap -arrow-.

Courtesy of AUDI

-- Free up the fuel hose from the brackets -1 and 3- and disconnect the connector coupling -2-. Refer to CONNECTOR COUPLINGS, DISCONNECTING .

-- Connect the Pressure Tester Kit:VAS 6550  to the fuel supply line with the Pressure Tester Kit - Hose 2:VAS 6550/2  .

Courtesy of AUDI

-- Attach the Pressure Tester Kit - Regulator Valve:VAS 6550/4  and hold the hose in a fuel-resistant measuring container.

-- Switch on the Pressure Tester Kit:VAS 6550  -item 1- by pressing the On/Off  button.

-- Open the shut-off valves -A and B-.

• The levers point in the flow direction.

-- Check if the shut-off valve -C- is closed.

• The lever is perpendicular to the flow direction.

-- Hold the hose in a fuel-resistant measuring container and secure the measuring container. A second technician may be required.

-- Connect the Vehicle Diagnostic Tester.

-- Switch the ignition on.

-- Select and start OBD  mode.

• Drivetrain
• Engine
• 01 - OBD-capable systems
• 01 - Engine Electronics
• Basic setting
• Drain fuel tank

-- Start the basic setting without measured values: the fuel pump starts.

-- To generate the initial pressure in the fuel system, turn the adjusting screw -1- on the Pressure Tester Kit - Regulator Valve:VAS 6550/4  until the correct initial pressure value is reached.

• Specified value: 4.5 bar (65.27 psi) pressure.

-- Do not turn the adjusting screw -1- any farther.

-- Press the Stop  button.

-- Empty the measuring container.

-- Hold the hose in a fuel-resistant measuring container and secure the measuring container. A second technician may be required.

-- To measure, press the Start  button again and let the fuel pump run for 15 seconds.

-- After 15 seconds, press the Stop  button.

-- Check the fuel delivery rate in the measuring container.

• Specified value: minimum delivery rate 800 cm³ /15 s.

If the minimum delivery rate is attained:

• The fuel delivery unit with the fuel filter, fuel pressure regulator and fuel supply line is OK.

If the minimum delivery rate is not obtained, it may be due to the following malfunctions:

• Fuel delivery unit with integrated fuel filter is faulty.
• Fuel pressure regulator in the fuel delivery unit is faulty.
• Fuel supply line is crushed.

B -  Pressure Test in the Fuel Supply Line

• Set up the equipment as if measuring for the fuel delivery rate.
• Vehicle Diagnostic Tester is still connected.

-- Switch on the Pressure Tester Kit:VAS 6550  -item 1- by pressing the On/Off  button.

-- Open the shut-off valves -A and B-.

• The levers point in the flow direction.

-- Check if the shut-off valve -C- is closed.

• The lever is perpendicular to the flow direction.

-- Hold the hose in a fuel-resistant measuring container and secure the measuring container. A second technician may be required.

-- Press Start  on the Vehicle Diagnostic Tester display: the fuel pump starts running.

-- If the fuel flows without bubbles, close the shut-off valve -B- so that the fuel pressure increases.

• The lever is perpendicular to the flow direction.

-- Read the fuel pressure on the Pressure Tester Kit:VAS 6550  :

• Specified value: 6.0 to 8.0 bar (87.02 to 116.03 psi).

-- Press the Stop  button.

If the specified value is obtained, even though the fuel delivery rate was not OK:

• Fuel filter in the fuel delivery unit is plugged or the fuel supply line is crushed.

If the specified value is not attained:

• Fuel delivery unit or fuel pressure regulator in the fuel tank is faulty.

C -  Checking Residual Pressure

-- Check the residual pressure and also for leaks by monitoring the decrease in pressure on the Pressure Tester Kit:VAS 6550  :

• There still must be a pressure of at least 3 bar (43.51 psi) after 10 minutes.

If the residual pressure drops below 3 bar:

• Check the fuel lines and their connections for leaks.
• The check valve in the fuel pump leaks: replace the fuel delivery unit. Refer to FUEL DELIVERY UNIT/FUEL LEVEL SENSOR, REMOVING AND INSTALLING .

Assembling

Assemble in the reverse order of removal.

• The ignition must be off.

-- Remove the Pressure Tester Kit:VAS 6550  with the connecting lines.

-- Attach the fuel supply line so that it clicks into place.

-- Press on the fuel supply line again and pull it to make sure the connector coupling is engaged correctly.