ignition AUDI A4 1998 B5 / 1.G AFC Engine Fuel Supply System Components Workshop Manual

20-3

Safety precautions


WARNING!

When removing and installing the fuel pump
or fuel level sensor from a filled or partially
filled fuel tank:

BEFORE beginning repairs, the suction pipe
of an exhaust extraction system must be
located near the fuel tank opening so that
escaping fuel vapors can be immediately
carried away.
If no exhaust extraction system is available,
a radial fan (motor located outside airflow)
with volume of at least 15 m3/hr (9 cfm) may
be used.
Wear fuel-resistant gloves whenever working
with open parts of the fuel system.

Be sure the ignition is switched OFF, when:
Disconnecting fuel injection system wiring
Connecting or disconnecting test equipment
leads

BEFORE cranking the engine at starting RPM
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(such as for compression testing) disable the
ignition and fuel injection systems:

Disconnect the ignition coil power output
stage.
Disconnect harness connectors from all fuel
injectors.
After the work is completed, erase
Diagnostic Trouble Code (DTC) memory.
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20-4

CAUTION!

BEFORE disconnecting the battery:

Stop the engine.
Be sure the ignition is switched OFF (also
applies when connecting the battery). Failure
to do so may damage the Engine Control
Module (ECM).
Be sure of the proper radio code (for vehicles
equipped with coded anti-theft radio).

Be sure the battery negative (-) cable is
disconnected, when:
Working on the electrical system
Resistance (spot) welding or electric arc
welding anywhere on the vehicle.

When connecting and disconnecting
electrical test equipment (LED voltage tester,
multimeter, etc.):
Be sure the ignition is switched OFF.
Use correct adapters from the VW 1594
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20-5

Flange and fuel level sensor, removing
and installing


Observe safety measures page 20
-3

Pay attention to rules of cleanliness page 20
-2 .

WARNING!

Fire hazard. DO NOT smoke or work near
heaters or have anything in the area that can
ignite fuel!

- Switch ignition on.

- Observe fuel gauge.

CAUTION!

The fuel tank should not be more than 2/3
full. Empty fuel tank, if necessary, using an
approved fuel cart.
Determine correct radio anti-theft coding
before disconnecting the battery.

Removing
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20-10

Fuel pump, testing


WARNING!

Fire hazard! DO NOT smoke or work near
heaters or have anything in area that can
ignite fuel!

Checking power supply

Battery fully charged
Fuse 28 OK
Test voltage supply to fuse 28 Repair
Manual, 2.8 Liter V-6 OBD II Fuel Injection
and Ignition, Repair Group 24

Fuel supply OK

- Switch ignition on.
Fuel pump must be heard to run briefly.
(Second person will be required for this if
surrounding noise level is too high).
If fuel pump does NOT run:

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20-12


- Disconnect fuel return line -1- at engine compartment bulkhead and
hold in measuring container.
- Connect remote control VAG 1348/3A with auxiliary cable VAG 1348/2
to fuse 28, connect positive (+) cable to battery.
- Operate remote control for 15 seconds (hold down button).

Fuel pump check valve, checking
Testing check valve Repair Manual, 2.8 Liter V-6 OBD II Fuel Injection
Ignition, Repair Group 24 - Compare quantity of fuel delivered with specified values for minimum
fuel delivery rate in graph, according to actual voltage at fuel pump.
*) - Minimum fuel delivery rate-fuel volume in cm3 (ml) delivered in15
seconds
**) - Voltage (V) at fuel pump with engine stopped, fuel pump running-
approx. 2 volts less than battery positive voltage (B+)
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