Checking fuel system pressurisation pump G6 - TDI vehicles — AUDI

🧭 Before you start

Fits: Audi A4 B9 (8W, 2015–)

• Special tools named: VAS 6551

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• Disregard (items 1, 3).
• Disregard (items 2, 3).
• Risk of fuel escaping.Cut-off valve (C) must be closed.The lever should point perpendicular to direction of flow. — Connect vehicle diagnostic tester.
• From this point on, do not turn adjuster screw (1).
• To find the precise cause of the fault, a pressure test must be performed on the fuel supply line as described below.

🔧 Engine codes this applies to

📋 Procedure

1. Observe test conditions .
2. Open tank flap.
3. Remove filler cap (arrow) for fuel filler neck.
4. Remove engine cover panel Engine10Engine cover panel; Removing and installing engine cover panel.
5. ⚠ The fuel system is pressurised.Risk of injury as fuel may spray out.Wear safety goggles.Wear protective gloves.Release pressure (wrap clean cloth around connection and open connection carefully). — Release hose clip (2) and detach fuel supply hose from fuel supply line to high-pressure pump. [Note: Disregard (items 1, 3).]

6. Attach connection fittingVAS 6551/5-1 to fuel supply hose (1), secure with hose clip and attach connection leadVAS 6551/2.
7. Attach connecting lineVAS 6551/2 to pressure tester (diesel)VAS 6551.
8. Attach pressure control valveVAS 6551/6 and hold end of hose into fuel-resistant measuring container.
9. Disconnect fuel supply hose (1) leading to high-pressure pump. Disconnecting plug-in connectors [Note: Disregard (items 2, 3).]
10. Connect pressure tester (diesel)VAS 6551 to fuel supply hose with connecting lineVAS 6551/7-2.
11. Attach pressure control valveVAS 6551/6 and hold end of hose into fuel-resistant measuring container.
12. Switch on pressure tester (diesel)VAS 6551(item 1) by pressing On/Off button. [Note: To measure the fuel delivery rate, pressure must first be built up in the fuel supply line; the fuel pump must then operate against this pressure during the measurement. This pressure can be built up using the pressure control valveVAS 6551/6 as follows:]
13. Open cut-off valves (A and B).
14. ⚠ Risk of fuel escaping.Cut-off valve (C) must be closed.The lever should point perpendicular to direction of flow. — Connect vehicle diagnostic tester.
15. Switch on ignition.
16. Select and start Diagnosis.
17. Select Own test button and select the following in succession from tree:
18. Press Start.
19. Build up pressure in fuel system by turning adjuster screw (1) on pressure control valveVAS 6551/6 until correct pressure is reached.
20. From this point on, do not turn adjuster screw (1).
21. Press Stop.
22. Drain measuring container.
23. For measurement, press Start again and let fuel pump run for 15 seconds.
24. Press Stop after 15 seconds.
25. Check amount of fuel delivered in measuring container. [Note: To find the precise cause of the fault, a pressure test must be performed on the fuel supply line as described below.]
26. Switch on pressure tester (diesel)VAS 6551(item 1) by pressing On/Off button.
27. Open cut-off valve (A).
28. ⚠ Risk of fuel escaping.Cut-off valves (B and C) must be closed.The levers should point perpendicular to direction of flow. — Press Start on vehicle diagnostic tester display to start the fuel pump.
29. Press Stop after 15 seconds.
30. Read fuel pressure off pressure tester (diesel)VAS 6551. [Note: To detect any faults in the fuel return line or in the relief valve of the high-pressure pump, a pressure test must be performed on the entire system as described below.Before disconnecting the measuring equipment, release the fuel pressure by opening the cut-off valves (B and C) and allowing fuel to drain off into a measuring container.]
31. Detach pressure control valveVAS 6551/6 and remove together with measuring container.
32. Connect connecting lineVAS 6551/5-2 to fuel supply line leading to high-pressure pump and to pressure tester (diesel)VAS 6551. [Note: In this way the pressure tester (diesel)VAS 6551 is connected into the fuel supply line.]
33. Detach pressure control valveVAS 6551/6 and remove together with measuring container.
34. Connect connecting lineVAS 6551/7-1 to fuel supply hose leading to high-pressure pump and to pressure tester (diesel)VAS 6551. [Note: In this way the pressure tester (diesel)VAS 6551 is connected into the fuel supply line.]
35. Switch on pressure tester (diesel)VAS 6551(item 1) by pressing On/Off button.
36. Open cut-off valves (A and B).
37. ⚠ Risk of fuel escaping.Cut-off valve (C) must be closed.The lever should point perpendicular to direction of flow. — Connect vehicle diagnostic tester.
38. Switch on ignition.
39. Select and start Diagnosis.
40. Select Own test button and select the following in succession from tree:
41. Press Start.
42. Read fuel pressure off pressure tester (diesel)VAS 6551. [Note: Before removing the pressure tester (1), release the fuel pressure by opening the cut-off valves (B, C) and allowing fuel to drain off into a measuring container.]
43. Detach pressure tester (diesel)VAS 6551 together with connecting lines.
44. Secure fuel supply line with hose clip and then pull to check that fuel supply line is properly secured.
45. Install engine cover panel Engine10Engine cover panel; Removing and installing engine cover panel.

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