Transfer Fuel Pump -G6-, CHECKING, TDI VEHICLES: Notes
Special tools and workshop equipment required
- Diesel Pressure Tester Kit:VAS 6551
with Diesel Pressure Tester Kit - Hose 2:VAS 6551/2
- Diesel Pressure Tester Kit - Adapter Set:VAS 6551/5
- Diesel Pressure Tester Kit - Pressure Regulator Valve:VAS 6551/6
- Diesel Pressure Tester Kit - Hose Adapter Set:VAS 6551/7
- 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-.
-- 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 Diesel Pressure Tester Kit - Adapter Set - Adapter 1:VAS 6551/5-1 to the fuel supply hose -1-, secure it with a hose clamp and attach the Diesel Pressure Tester Kit - Hose 2:VAS 6551/2 .
-- Connect the Diesel Pressure Tester Kit - Hose 2:VAS 6551/2 to the Diesel Pressure Tester Kit:VAS 6551 .
-- Attach the Diesel Pressure Tester Kit - Pressure Regulator Valve:VAS 6551/6 and hold the hose in a fuel-resistant measuring container.
-- Hold the hose in a fuel-resistant measuring container and secure the measuring container. A second technician may be required.
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 Diesel Pressure Tester Kit:VAS 6551 to the fuel supply hose using the Diesel Pressure Tester Kit - Hose Adapter:VAS 6551/7-2 .
-- Attach the Diesel Pressure Tester Kit - Pressure Regulator Valve:VAS 6551/6 and hold the hose in a fuel-resistant measuring container.
-- Hold the hose in a fuel-resistant measuring container and secure the measuring container. A second technician may be required.
Continuation for All Vehicles:
-- Switch on the Diesel Pressure Tester Kit:VAS 6551 -item 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. The initial pressure is adjusted using the Diesel Pressure Tester Kit - Pressure Regulator Valve:VAS 6551/6 as follows:
-- Open the shut-off valves -A and B-.
- The levers point in the flow direction.
Risk of fuel leaking.
- 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 systems
- 0001 - Engine Electronics
- 0001 - Engine electronics, functions
- 0001 - Fuel pump activation
- Perform the test
-- Start the fuel pump and let it run for 15 seconds.
-- To generate the initial pressure in the fuel system, turn the adjusting screw -1- on the Diesel Pressure Tester Kit - Pressure Regulator Valve:VAS 6551/6 until the correct initial pressure value is reached.
- Specified value: 4.5 bar (65.27 psi) pressure.
If the 15 second start is not sufficient to adjust the initial pressure, repeat the procedure.
-- Do not turn the adjusting screw -1- any farther.
-- Empty the measuring container.
-- Start the fuel pump and let it run for 15 seconds.
-- Check the fuel delivery rate in the measuring container.
- 4-cylinder specified value: minimum delivery rate 750 cm3 /15 s.
- 6-cylinder specified value: minimum delivery rate 1000 cm3 /15 s.
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 2.0L TDI vehicles , 3.0L TDI vehicles .
If the minimum delivery rate is not obtained, it may be due to the following malfunctions:
- The fuel pump or fuel pressure regulator in the fuel tank is faulty.
- Fuel line is pinched.
- The fuel filter is clogged.
To more accurately locate the malfunction, perform the "pressure test in the fuel supply line" described in the following.
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 Diesel Pressure Tester Kit:VAS 6551 -item 1- by pressing the On/Off button.
-- Open the shut-off valve -A-.
- The lever points in the flow direction.
Risk of fuel leaking.
- 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 on the Diesel Pressure Tester Kit:VAS 6551 .
- Specified value: 6.0 to 8.0 bar (87.02 to 116.03 psi).
If the specified value is obtained, even though the fuel delivery rate was 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 allowing the fuel drain into the measuring container before disassembling the measuring system.