Transfer Fuel Pump -G6-, Checking

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Special tools and workshop equipment required

Pressure Tester Kit VAS 6550 with Pressure Tester Kit - Hose 2 VAS 6550/2
Pressure Regulator Valve VAS 6550/4
Vehicle Diagnostic Tester
Measuring container, fuel-resistant

A - Check Fuel Delivery Rate

NOTE:

The illustration shows the test sequence on a 2.0L TFSI engine.

-- Follow all test requirements, refer to TEST CONDITIONS .

-- Release and open the fuel filler door.

-- Clean the area around the fuel filler tube.

NOTE:

Ignore item -3-.

-- Remove the cap -2- for the fuel filler -1-.

Fig 1: Identifying Cap -2-

Courtesy of AUDI OF AMERICA, LLC

Version 1:

WARNING:

There is a risk of injury because the fuel is under high pressure.

To reduce pressure in fuel system, lay a clean cloth around the connector and carefully loosen connector.

-- Disconnect the fuel line -1-. Disconnect the connector couplings, refer to CONNECTOR COUPLINGS, SEPARATING .

Fig 2: Identifying Fuel Line

Courtesy of AUDI OF AMERICA, LLC

Version 2:

WARNING:

There is a risk of injury because the fuel is under high pressure.

To reduce pressure in fuel system, lay a clean cloth around the connector and carefully loosen connector.

-- Disconnect the fuel line. Disconnect the connector couplings, refer to CONNECTOR COUPLINGS, SEPARATING .

Fig 3: Identifying Fuel Line

Courtesy of AUDI OF AMERICA, LLC

Continuation for All Vehicles:

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

-- Connect the Pressure Regulator Valve VAS 6550/4 and hold the hose in a fuel-resistant measuring container.

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

Fig 4: Identifying Diesel Pressure Tester Kit VAS 6550 With Diesel Pressure Tester Kit - Hose 2 VAS 6550/2

Courtesy of AUDI OF AMERICA, LLC

NOTE:

In order to measure the fuel delivery rate, there must be an initial pressure inside the fuel line against which the fuel pump must work during the measuring. Adjust the initial pressure using the Pressure Regulator Valve VAS 6550/4 as follows:

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

The levers point in the direction of flow.

CAUTION:

Risk of fuel leak.

The shut-off valve -C- must be closed.
The lever is perpendicular to the direction of flow.

-- Connect the Vehicle Diagnostic Tester.

-- Turn on the ignition and select the following menu items on the Vehicle Diagnostic Tester:

Fig 5: Identifying Shut-Off Valves A And B On Pressure Tester Kit

Courtesy of AUDI OF AMERICA, LLC

OBD
Engine electronics
Basic setting
Empty fuel tank

-- Press Start : The fuel pump starts.

-- Turn the adjusting screw -1- on the Pressure Regulator Valve VAS 6550/4 to create an initial pressure in the fuel system until the correct initial pressure value is reached.

Fig 6: Identifying Pressure Regulator Valve Adjusting Screw

Courtesy of AUDI OF AMERICA, LLC

Specified value: 4.3 bar (62.3 psi) positive pressure.

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

-- Press the Stop button.

-- Empty measuring container.

-- 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 amount of fuel 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 Minimum Delivery Quantity is not Obtained, the Following Malfunctions May Be Present:

Fuel delivery unit faulty.
The fuel filter, integrated in the sealing flange fuel pressure regulator is blocked or faulty.
Fuel supply line is pinched.

NOTE:

To locate the fault in more detail, perform the "pressure test in the fuel supply line", described as follows.

B - Pressure Test in the Fuel Supply Line

Fig 7: Identifying Shut-Off Valves A And B On Pressure Tester Kit

Courtesy of AUDI OF AMERICA, LLC

Connect the measuring setup as if measuring the delivery quantity.
Vehicle Diagnostic Tester still connected.

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

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

The levers point in the direction of flow.

CAUTION:

Risk of fuel leak.

The shut-off valve -C- must be closed.
The lever is perpendicular to the direction of flow.

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

-- If the fuel flows without bubbles, close the drain -B-, so that the fuel pressure increases.

The lever is perpendicular to the direction of flow.

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

Specified value: 5.0 to 8.0 bar (72.5 to 116 psi).

-- Press the Stop button.

If Specified Value Is Obtained, Although the Fuel Delivery Unit is Not OK.

The fuel filter integrated in the sealing flange is blocked or the fuel supply line is crushed.

If the Specification is Not Attained:

The fuel delivery unit or the fuel pressure regulator integrated in the fuel pressure regulator is faulty.

C - Checking Residual Pressure

-- Watch the pressure fall on the Pressure Tester Kit VAS 6550 while checking the holding pressure and checking for leaks:

After 10 minutes there must be a residual pressure of at least 3 bar (43 psi).

If the Residual Pressure Drops Below 3 bar (43 psi):

Check fuel lines and their connections for leaks.
There is a leak at the check valve in the fuel pump: Replace the fuel delivery unit, refer to FUEL DELIVERY UNIT/FUEL LEVEL SENSOR, REMOVING AND INSTALLING .

Assembling

Assembly is performed in the reverse order of disassembly, noting the following:

The ignition must be off.

NOTE:

Decrease the fuel pressure by opening the drains -B, C- and letting the fuel run into the measuring container before removing the pressure gauge -1-.

Fig 8: Identifying Shut-Off Valves A And B On Pressure Tester Kit

Courtesy of AUDI OF AMERICA, LLC

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

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

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