AUDI A4 1998 B5 / 1.G Fuel Supply System Servicing Guidelines Workshop Manual

20-1


Fuel supply system, servicing
guidelines

Safety precautions


WARNING!

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

BEFORE beginning work, place exhaust
extraction system suction pipe near fuel tank
opening so escaping fuel vapors can be
immediately sucked off.
If no exhaust extraction system is available,
use a radial fan (with motor located outside
airflow) with volume of at least 9 cfm.
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.
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BEFORE cranking the engine at starting RPM
(such as compression testing) disable the
fuel injection and ignition 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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20-2

WARNING!

Fire hazard! Do NOT have anything in the
area that can ignite gasoline!
Fuel system is under pressure! Before
opening, place clean cloths around the
connections to be opened. Carefully loosen
the connections to relieve pressure.
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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 VW 1594
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connector test kit.

Always refer to the latest parts catalog to
ensure that you use original equipment fuel
hose clamps.
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20-4

Rules of cleanliness


CAUTION!

Whenever working on the fuel supply and fuel
injection systems, carefully observe the
following five rules of cleanliness:
1.- Thoroughly clean fuel system lines and hose
connections and surrounding area before
disconnecting.
2.- Place removed components on a clean
surface and cover them. Use plastic sheeting or
paper. Do not use fluffy rags that could leave
lint.
3.- Carefully cover or seal any components that
have been opened if repairs are not carried out
immediately.
4.- Install only clean parts. Do not remove
replacement parts from the packaging until
immediately before they are installed.
Do not use parts that have been stored without
packaging (from toolboxes, for example).
5.- When fuel system is opened avoid working
with compressed air whenever possible. Avoid
moving the vehicle if possible
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20-5
Observe following points before working on the
fuel supply system

CAUTION!

Obtain the radio Anti-theft code from the
customer before disconnecting the Battery
Ground strap.

With ignition switched OFF, disconnect Battery
Ground strap.
Open the fuel filler cap briefly and close
again.
Observe the following precautions when
removing or installing components from a filled or
partially filled fuel tank.

WARNING!

Empty the fuel tank before removal! If it is not
empty, the weight and sloshing fuel could
lead to injury, component damage or possible
fuel spillage.
Fuel tank must not be filled more than
1/3
maximum.

Reduce fuel quantity using fuel cart, if
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necessary.
Do NOT allow fuel to contact skin! Wear fuel-
resistant gloves!
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