Transfer Fuel Pump -G6-, CHECKING, TFSI VEHICLES
Special tools and workshop equipment required
- Pressure Tester Kit: VAS6550 with Pressure Tester Kit - Hose 2: VAS6550/2
- Pressure Tester Kit - Adapter Set: VAS6550/3
- Pressure Regulator Valve: VAS6550/4
- 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 [CXYA] or ENGINE COVER, REMOVING AND INSTALLING [CZSE] .
-- Disconnect the fuel hose -2-. Disconnect the connector coupling. Refer to CONNECTOR COUPLINGS, DISCONNECTING .
-- Connect the : VAS6550 to the fuel supply line with the : VAS6550/2 .
-- Attach the : VAS6550/4 and hold the hose in a fuel-resistant measuring container.
-- Switch on the : VAS6550 -1- by pressing the On/Off button.
- To measure the fuel delivery rate, an initial pressure must be created in the fuel line which the fuel pump must work against during measurement. The initial pressure is adjusted using the : VAS6550/4 as follows:
-- 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.
-- Connect the Vehicle Diagnostic Tester.
-- Switch the ignition on.
-- Select and start OBD .
- 0001 - Engine electronics J623
- 0001 - basic setting
- 0001 - Drain fuel tank
-- Press Start .
- The fuel pump starts.
-- To generate the initial pressure in the fuel system, turn the adjusting screw -1- on the : VAS6550/4 until the correct initial pressure value is reached.
- 6-cylinder specified value: 4.5 bar (65.27 psi) pressure
- 8-cylinder specified value: 5.5 bar (79.77 psi) pressure
-- Do not turn the adjusting screw -1- any farther.
-- Press the Stop button.
-- Empty the 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 fuel delivery rate in the measuring container.
- 6-cylinder specified value: minimum delivery rate 800 cm3 /15 s.
- 8-cylinder specified value: minimum delivery rate 825 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.
TIP:
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 : VAS6550 -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.
-- 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 : VAS6550 :
- 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 : VAS6550 :
- 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 (43.51 psi):
- 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, REMOVING AND INSTALLING, TDI VEHICLES .
Assembling
Assemble in the reverse order of removal. Note the following:
- The ignition must be off.
- Decrease the fuel pressure by opening the shut-off valves -B and C- and allowing the fuel drain into the measuring container before removing the pressure tester -1-.
-- Remove the : VAS6550 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.