Transfer Fuel Pump -G6-, Checking, TDI Vehicles: Notes
Special tools and workshop equipment required
- Diesel Pressure Tester Kit :VAS6551 with Diesel Pressure Tester Kit - Hose 2 :VAS6551/2
- Diesel Pressure Tester Kit - Adapter Set :VAS6551/5
- Pressure Regulator Valve :VAS6551/6
- Diesel Pressure Tester Kit - Adapter Set :VAS6551/7
- Vehicle Diagnostic Tester
- Fuel-Resistant Measuring Container
A - Checking Fuel Delivery Rate
-- Follow all test conditions. Refer to TEST CONDITIONS .
-- Open the fuel filler door.
-- Remove the fuel filler cap -arrow-.
-- Remove the engine cover. Refer to ENGINE COVER, REMOVING AND INSTALLING .
The fuel system is under pressure.
Risk of injury from fuel spraying out.
- Wear protective eyewear.
- Wear safety gloves.
- Reduce the pressure: Place clean cloths around the connection point and carefully open the connection point.
2.0L TDI Vehicles
-- Loosen the hose clamp -2- and remove the fuel supply hose from the fuel supply line to the high pressure pump.
-- Connect the :VAS6551/5-1 to the fuel supply hose -1-, secure it with a hose clamp and attach the :VAS6551/2 .
-- Connect the :VAS6551/2 to the :VAS6551 .
-- Attach the :VAS6551/6 and hold the hose in a fuel-resistant measuring container.
3.0L TDI Vehicles
-- Disconnect the fuel supply hose -1- to the high pressure pump. Disconnect the connector couplings. Refer to CONNECTOR COUPLINGS, DISCONNECTING .
-- Connect the :VAS6551 with the :VAS6551/7-2 on the fuel supply hose.
-- Attach the :VAS6551/6 and hold the hose in a fuel-resistant measuring container.
Continuation for All Vehicles
-- Switch on the :VAS6551 -1- by pressing the On/Off button.
To measure the fuel delivery rate, there must be an initial pressure inside the fuel supply line against which the fuel pump must work during the measuring. This initial pressure is adjusted using the :VAS6551/6 as follows:
-- Open the shut-off valves -A and B-.
- The lever points in the flow direction.
Risk of fuel leak.
- The shut-off valve -C- must be closed.
- The lever is perpendicular to the flow direction.
-- Connect the Vehicle Diagnostic Tester.
-- Switch the ignition on.
-- Select Diagnostic and start.
-- Select the Select individual test button and select the following tree structure consecutively:
- Drivetrain
- Select the engine code and engine
- 0001 - OBD-capable system
- 0001 - Engine electronics
- 0001 - Engine electronics, functions
- 0001 - Fuel pump activation
- Preform the test
-- Start the fuel pump and let it run for 15 seconds.
-- Turn the adjusting screw -1- on the :VAS6551/6 to create an initial pressure in the fuel system until the correct initial pressure value is reached.
- Specified value: 4.5 bar (65.27 psi) pressure.
-- Select Diagnostic and start.
-- Select the Select individual test button and select the following tree structure consecutively:
- Drivetrain
- Select the engine code and engine
- 0001 - OBD-capable system
- 0001 - Engine electronics
- 0001 - Engine electronics, functions
- 0001 - Fuel pump activation
- Preform the test
-- Start the fuel pump and let it run for 15 seconds.
If the minimum delivery rate is attained:
- Fuel supply line, fuel filter and fuel pump are OK.
- However, there may be a malfunction in the fuel return. For Fault Finding, perform an "Entire system pressure test". Refer to C - Entire System Pressure Test, 2.0L TDI Vehicles and C - Entire System Pressure Test, 3.0L TDI Vehicles .
If the minimum delivery rate is not obtained, the following malfunctions may be present:
- The fuel pump or fuel pressure regulator in the fuel tank is faulty.
- Fuel line is pinched.
- The fuel filter is clogged.
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
- Connect the measuring setup as if measuring the fuel delivery rate.
- Vehicle Diagnostic Tester still connected.
-- Switch on the :VAS6551 -1- by pressing the On/Off button.
-- Open the shut-off valve -A-.
- The lever points in the flow direction.
Risk of fuel leak.
- The shut-off valves -B and C- must be closed.
- The levers face perpendicular to the flow direction.
-- Start the fuel pump and let it run for 15 seconds.
-- Read the fuel pressure in the Diesel Pressure Tester Kit :VAS6551 .
- Specified value: 6.0 to 8.0 bar (87.02 to 116.03 psi).
If the specified value is obtained, although the fuel delivery rate is not OK.
- Fuel supply line is crushed.
- The fuel filter is clogged.
If the specified value is not attained:
- The fuel pump or fuel pressure regulator in the fuel tank is faulty.
To also locate malfunctions in the fuel return line or the high pressure pump overflow valve, the "Entire system pressure test" must be performed as described in the following.
Decrease the fuel pressure by opening the shut-off valves -B and C- and letting the fuel run into the measuring container before replacing the measuring system.