2000 AUDI A4 fuel

20-172


Note:
Fuel system pressurization depends on volume of fuel system and
amount of fuel in tank.
If fuel system pressurization does not stabilize:
CAUTION!
Clamp only soft rubber lines when isolating a leak. To avoid risk of
damage, never clamp hard plastic lines!
Note:
Any flow shown on flow meter indicates a leak. Flow before flow meter
flag set at vehicle leak standard may indicate a sporadic DTC.
If flow meter on tester registers flow near or above preset pressure: - Attach fuel cap adapter to filler neck (arrow) and test hose to adapter.
- Turn control valve from "Hold" to "Test".
- Allow fuel system to pressurize.
- Verify all fuel system outlets have been sealed before continuing.

- Clamp off hose (arrow) leading from EVAP purge regulator valve -N80-
to intake manifold (pictured: AHA engine in A6).
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If flow stops:

- Replace EVAP purge regulator valve -N80- and
repeat test before continuing.
If meter indicates no flow after test:

- Perform a quality check and return vehicle to
customer.
If flow continues, proceed as follows:

Method 1: Locate leak with smoke generator

- Connect leads from smoke generator to vehicle
battery.

- Use smoke generator trigger to charge fuel
system with smoke.

- Inspect complete EVAP system for escaping
smoke.
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Method 2: Locate leak with ultrasonic tester
If leak cannot be located:
CAUTION!
Clamp only soft rubber lines when isolating a leak. To avoid risk of
damage, never clamp hard plastic lines! General search: tester only
Localized search: tester with extension (on left in illustration)
- Disconnect and plug or clamp shut EVAP lines to isolate fuel tank,
using Special Tool No. 3094 or equivalent, before continuing.
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If flow stops:

- Reconnect EVAP lines to search area that was
isolatedl
If leak or source of fuel odor cannot be found:

- Contact Audi Dealer Technician Helpline.

CAUTION!

Under no circumstances should the vehicle
be returned to the customer without proper
diagnosis and repair.
When leak has been located:

- Repair leak and repeat EVAP system test.

- Perform quality check and return vehicle to
customer.

Note:

Because leak may be at top of fuel tank, it may
not be possible to locate through fuel
pump/sending unit access plate.
Fuel tank may need to be lowered to locate the
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EVAP system leak detection circuit,
schematic diagram (vehicles with 1.8 ltr.
turbo engine)

Repair Manual, 1.8 Liter 4-Cyl. 5V Turbo Fuel
Injection & Ignition, Repair Group 24 1 -
Check valve
Location (light/dark side): as shown in
illustration
2 -
EVAP canister purge regulator valve -N80-Location: in engine compartmentChecking
3 -
Bleed line
From EVAP canister purge regulator valve
-N80-
LocationRight side under floor panFront-wheel drive: on floor pan in area of
fuel tank All-wheel drive: on fuel tank in area of fuel
tank
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EVAP system leak detection circuit,
schematic diagram (vehicles with 2.8 ltr.
engine)

Repair Manual, 2.8 Liter V6 5V Fuel Injection &
Ignition, Repair Group 24 1 -
Throttle actuator control module -J338-
2 -
EVAP canister purge regulator valve -N80-Location: in engine compartmentChecking:
3 -
Bleed line
From EVAP canister to EVAP canister
purge regulator valve -N80-
LocationOn right side under floor panVehicles with front-wheel drive: mounted
on floor pan in area of fuel tank Vehicles with all-wheel drive: mounted on
fuel tank
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4 -
Bleed line
To gravity valve on fuel tank
5 -
EVAP canister Location: in bottom of spare tire well
6 -
Connecting hose LDP / EVAP canisterPressure side
7 -
Air filter For LDP
8 -
LDP -V144 Location: in left rear wheel house behind
wheel well Page 20
-130

9 -
Vacuum hose
LDP / throttle actuator control module
10 -
T - piece Location Fig. 1
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EVAP system leak detection circuit,
schematic diagram (vehicles with 2.7 ltr.
turbo engine)

Repair Manual, 2.7 Liter V6 5V BiTurbo Fuel
Injection & Ignition, Engine Code(s): APB, Repair Group 24
1 -
To air intake before both turbo chargers
2 -
Check valve Installation position: Arrow at housing
indicates flow-through direction.
3 -
Evaporative Emission (EVAP) canister
purge regulator valve -N80- Location: On right side of engine
compartment Checking:
4 -
Vent line
From EVAP canister to EVAP canister
purge valve regulator valve -N80 Installation position: On right side on
vehicle under-side. Attached to fuel tank.
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