fuel pump AUDI A4 1998 B5 / 1.G AFC Engine Fuel Syst

24-20


Fuel system pressure and
residual pressure, checking

CAUTION!

Fire hazard! Do not smoke, work near heaters
or open flame, or have anything in the area
that could ignite fuel.

Checking requirements:

Fuel pump relay OK; checking page 24
-24

Fuel pump OK:

Repair Manual, 2.8 Liter V6 2V Engine
Mechanical, Engine Code(s): AFC, Repair Group 20


Correct fuel filter installed
Battery positive voltage (B+): 12 volts
minimum

Checking system pressure

-
Connect VAG 1318 pressure tester between fuel supply and fuel return
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24-21

- Use scan tool "Output Diagnostic Test Mode"
function 03 to trigger Fuel Pump (FP) relay -J17-
Repair Group 01. If fuel pump does not run:

- Check fuel pump:

Repair Manual, 2.8 Liter V6 2V Engine
Mechanical, Engine Code(s): AFC, Repair Group 20


Specified value: 3.8 to 4.2 bar (55 - 61 psi)
If the specified value is not obtained:

- Replace fuel pressure regulator and perform
pressure test again.
If the value is again not obtained:

- Check whether fuel pump or supply line is
damaged (e.g. pinched), and replace if
necessary.
If the specified value is exceeded:

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24-23

Residual pressure, checking
Residual pressure 10 minutes after stopping
engine:

With cold engine: 2.2 bar (32 psi) minimum
With a hot engine: 3.0 bar (44 psi) minimum

Note:
The pressure increase for a hot engine is caused
by fuel expansion and is normal.
If residual pressure is too low:

- Check pressure tester connections for leaks.

- Check fuel lines for leaks.

- Check fuel pump check valve:

Repair Manual, 2.8 Liter V6 2V Engine
Mechanical, Engine Code(s): AFC, Repair Group 20


- Check fuel injectors for leaks page 24
-33
.
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pressure and residual
pressure, checkin
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If there are no leaks and the fuel pump check
valve is OK:

- Replace fuel pressure regulator and repeat
residual pressure test.
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ystem
pressure and residual
pressure, checkin
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play?action=Goto&t
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pair&id=AUDI.B5.FU01.24.4