Transfer Fuel Pump - G6-, Checking: Notes
Special Tools And Workshop Equipment Required
- Diesel Pressure Tester Kit:VAS6551 with Diesel Pressure Tester Kit - Hose 2:VAS6551/2
- Pressure Regulator Valve:VAS6551/6
- Vehicle Diagnostic Tester
- Measuring container, fuel-resistant
A - Check fuel delivery rate
-- Follow all test requirements. Refer to TEST CONDITIONS .
-- Open the fuel filler door.
-- Remove the fuel filler cap -arrow-.
Very hot fuel can burn your skin.
- In extreme cases the temperature of the fuel lines and/or the fuel can go up to 100 °C. Let the fuel cool down before opening any line connections otherwise there is a danger of scalding.
- Wear safety gloves
- Wear protective eyewear.
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- by pushing the hose coupling downward -arrow A- first and then pressing the release buttons -B arrows-.
-- Remove the hose coupling with the release buttons pressed.
Ignore -item 2-.
-- Connect the Diesel Pressure Tester Kit:VAS6551 with the Diesel Pressure Tester Kit - Hose 2:VAS6551/2 to the fuel supply line.
-- Attach the Pressure Regulator Valve:VAS6551/6 and hold the hose in a fuel-resistant measuring container.
-- Switch on the Diesel Pressure Tester Kit: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 Pressure Regulator Valve:VAS6551/6 as follows:
-- Open the shut-off valves -A and B-.
- The levers point in the direction of flow.
Risk of fuel leak.
- The shut-off valve -C- must be closed.
- The level 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:
- OBD
- Engine Electronics
- Basic Setting
- Transfer Fuel Pump Test
-- Press Start : The fuel pump starts.
-- Turn the adjusting screw -1- on the Pressure Regulator Valve:VAS6551/6 to create an initial pressure in the fuel system until the correct initial pressure value is reached.
- Specified value: 4.0 bar 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 600 cm3 /15 s.
If the minimum delivery rate is attained:
- The fuel supply with the 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 .
If minimum delivery quantity 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.
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 delivery quantity.
- Vehicle Diagnostic Tester still connected.
-- Switch on the Diesel Pressure Tester Kit:VAS6551 -1- by pressing the On/Off button.
-- Open the shut-off valve -A-.
- The lever points in the direction of flow.
Risk of fuel leak.
- The shut-off valves -B and C- must be closed.
- The levers face perpendicular to the flow direction.
-- Press Start on the display of the Vehicle Diagnostic Tester: The fuel pump starts.
-- After 15 seconds, press the Stop button.
-- Read the fuel pressure in the Diesel Pressure Tester Kit:VAS6551 .
- Specified value: at least 4.0 bar
If specified value is obtained, although the fuel delivery unit is not OK.
- Fuel supply line is pinched.
If the specification 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.
Before replacing the measuring system, reduce the fuel pressure by opening the shut-off valves -B and C- and allowing the fuel to drain into the measuring container.
-- Disassemble the Pressure Regulator Valve:VAS6551/6 and remove it with the measuring container.