Checking delivery rate of fuel pumps - vehicles with fuel system without fuel return line — AUDI

🧭 Before you start

Fits: Audi A8 D3 (4E, 2002–2010)

• Special tools named: V.A.G 1318/26, V.A.G 1348, V.A.G 1348/3
• Renewed: relevant fuel delivery unit

Don't miss

• Disregard (item 1).
• Disregard (item 2).
• Connect contact (1) (positive) of fuel delivery unit (left-side) and fuel delivery unit (right-side) to battery "“+”" via an improvised test lead. For safety reasons an in-line fuse (A) (10 A) must be connected into the lead.
• Voltage at fuel pump with engine stationary and pump running is approx. 2 volts less than battery voltage.

🔧 Engine codes this applies to

📐 20 workshop diagrams for ASN

Real factory drawings for this job — timing marks, bolt locations and routing. Locked in the free view.

📋 Procedure

1. Observe test conditions .
2. ⚠ Observe safety precautions . — Remove luggage compartment side trim cover (right-side) (arrows).
3. Remove cover (2) over battery. [Note: Disregard (item 1).]
4. Remove luggage compartment floor covering.
5. Detach cover for flange (left-side) (arrows).

6. Unplug electrical connector (2) on flange (left-side). [Note: Disregard (item 1).]
7. Unscrew cover for flange (right-side) (arrows).
8. Unplug electrical connector (2) on flange (right-side). [Note: Disregard (item 1).]
9. ⚠ Rules for cleanliness when working on the injection system . — Disconnect fuel return line (1) from flange by pressing release tabs. [Note: Disregard (item 2).]
10. Fit adapter V.A.G 1318/26 onto disconnected fuel pipe (1) and hold adapter hose in measuring container.
11. Connect remote controlV.A.G 1348/3A for V.A.G 1348 with adapter cable V.A.G 1348/3-3 to contact (4) (earth) of fuel delivery unit (left-side) and fuel delivery unit (right-side) using test leads from auxiliary measuring setV.A.G 1594C.
12. Connect crocodile clip to earth point next to battery.
13. Connect contact (1) (positive) of fuel delivery unit (left-side) and fuel delivery unit (right-side) to battery "“+”" via an improvised test lead. For safety reasons an in-line fuse (A) (10 A) must be connected into the lead.
14. Remove filler cap from fuel filler neck.
15. Press remote control button for 15 seconds.
16. Compare amount of fuel delivered with minimum delivery shown in diagram (cm3/15 sec.). [Note: Voltage at fuel pump with engine stationary and pump running is approx. 2 volts less than battery voltage.] [Note: As there is hardly any difference in the fuel delivery rate if only one of the two fuel pumps is working (because of the hose connections inside the tank), it is difficult to diagnose a defective pump by just measuring the delivery rate.]
17. Unplug the electrical auxiliary lead at the fuel delivery units (one at a time).
18. Measure delivery rate of fuel delivery unit located on the opposite side.
19. Renew the relevant fuel delivery unit.

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