2000 AUDI A8 engine

24-96
If the fuel pump does not respond:

- Check fuel pump relay actuation page 24
-
99
.
If the LED test light does not light up:

- Repeat test at other terminal of fuse 28.

If the LED light still does not light up:
- Check wiring for open or short circuits between fuse 28 and terminal 30
at relay position 6, using the applicable wiring diagram. Repair wiring
as necessary.

Specified value: max. 1.5

Note:
This step lets the fuel pump run without the engine running. The closed
throttle position switch must be closed during the test, or the selected fuel
injector will discharge fuel when it is actuated 5 times. - Connect VAG1527B LED voltage tester between Ground and one of
the two terminals for fuse 29.
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24-97
If the LED test light does not light up:

- Repeat test at other terminal of fuse 29.

If the LED test light still does not light up:
- Check wiring for open circuit between fuse 29 and terminal 30 at relay
position 6, using the applicable wiring diagram. Repair wiring as
necessary.

Specified value: max. 1.5

Note:
This step lets the fuel pump run without the engine running. The closed
throttle position switch must be closed during the test, or the selected fuel
injector will discharge fuel when it is actuated 5 times. - Connect VAG1527 LED voltage tester between Ground and one of the
two terminals of fuse 34.
- Initiate output Diagnostic Test Mode (DTM) and advance to test of
cylinder 1 fuel injector -N30- page 01
-51
.

LED test light must light up
Fuel pump relay must be activated
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Fuse for fuel injectors OK
Engine speed (RPM) sensor OK
Fuel pump relay OK
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24-108

Checking injection amount

- Insert injector to be tested into measuring glass of VAG1602 fuel
analyzer.
- Connect one terminal of injector being tested to engine ground using
test lead from VAG1594.

Note:
This step lets the fuel pump run without the engine running. The closed
throttle position switch must be closed during the test, or the selected fuel
injector will discharge fuel when it is actuated 5 times. - Connect second terminal of injector to B+ using VAG1348/3A remote
control, VAG1348/3-2 adapter wire and an auxiliary wire.
- Conduct output DTM, actuating cylinder 1 injector -N30- page 01
-51

(fuel pump must be running).
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24-110

Checking for leaks

- Conduct output DTM, actuating cylinder 1
injector -N30- page 01
-51
(fuel pump must be
running).

Note:
This step lets the fuel pump run without the
engine running. The closed throttle position
switch must be closed during the test, or the
selected fuel injector will discharge fuel when it is
actuated 5 times.

- Visually check injector for leaks.

With fuel pump running, only 1 to 2 drops can
drip in a minute (per injector).
If fuel loss is greater:

- Replace leaking injector
Installation of the injectors is in reverse order of
removal.

- Replace O-rings on all injectors and coat O-rings
lightly with clean engine oil.

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24-112

Checking

Note:
Shut-off valve of pressure tester must be open (lever parallel to direction
of flow).
Note:
For the following test, do not let the engine run unnecessarily with the
vacuum hose removed, since the higher fuel pressure causes enrichment
of the fuel air mixture. The richer mixture could exceed the O2S control
limits and therefore cause a DTC to be stored.
Note:
If, during the following pressure test, fuel leaks from the vacuum
connection of the fuel pressure regulator, replace the fuel pressure
regulator. - Connect pressure tester VAG1318 between fuel supply line and fuel
rail using adapters 1318/7, 1318/10 and 1318/13.
- Remove vacuum line from fuel pressure regulator (to intake manifold)
and block line (using VW 3093).
- Switch off all electrical consumers (rear defrost, A/C etc.).
- Start engine and let idle.
- Measure fuel pressure.
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24-114
If there is no leak and vacuum connection has no
obstruction:

- Replace fuel pressure regulator.

Checking residual pressure

- Check residual pressure 10 minutes after
shutting off engine.


Cold engine (min.): approx. 2.2 bar (31.9
psi)

Warm engine (min.): approx. 3.0 bar (43.5
psi)

Note:
The higher pressure with a warm engine, caused
by fuel expansion, is normal.
If the specified value is not attained:

- Start engine and, after fuel pressure has
increased, switch ignition off.

- Close shut off valve on VAG1318 pressure
tester.
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24-116

Evaporative Emissions (EVAP) canister
purge regulator valve, checking


WARNING!

Whenever carrying out work on the fuel
supply and/or fuel injection systems, read
and carefully follow the Cautions, Warnings,
and rules of cleanliness page 24-9 .

Note:
Component locations page 24
-1

Required special tools and test equipment

VAG1551 or VAG1552 Scan Tool (ST) with
VAG1551/3 adapter cable

Test conditions
Engine coolant temperature at least 80 C
(176 F)

Function check

- Connect VAG1551 or VAG1552 scan tool and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with engine
running at idle) page 01
-8 .
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