Checking tandem pump and fuel pump, engine code AJS: VW Phaeton 4.9 TDI (AJS)

🧭 Before you start

Fits: VW Phaeton (3D)

• Renewed: tandem pump or fuel pump

Don't miss

• After pressure gauge has been disconnected, tighten supply line or plug to 27 Nm.

🔧 Engine codes this applies to

📋 Procedure

1. ⚠ The tandem pump may, under no circumstances, be dismantled as the vacuum part could malfunction. This would result in the failure of the brake booster. — Connect tandem pump testerVAS 5187 to test connection for cylinder bank 1 (1) or to test connection for cylinder bank 2 (2).
2. Remove fuel filter .
3. Connect tandem pump testerVAS 5187 to supply line for cylinder bank 1 (1) or to supply line for cylinder bank 2 using adapter from adapter setVAS 5187/6.
4. Install fuel filter .
5. Run the engine at idling speed.

6. Connect .
7. Select Vehicle self-diagnosis.
8. Select 01 - Engine.
9. Select 08 - Read measured value block.
10. Select display group 1 and confirm your entry by pressing the Q button.
11. Read off idling speed in display field 1.
12. Increase speed to 1500 rpm.
13. Observe pressure indicated on pressure gauge.
14. Using a hose clip, clamp off return line between fuel filter and tandem pump.
15. Repeat check.
16. Tandem pump is OK. Renew unit injector O-rings 23.
17. Renew tandem pump or fuel pump .
18. Press ← button.
19. Select 06 - End output. [Note: After pressure gauge has been disconnected, tighten supply line or plug to 27 Nm.]

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