Overview of fuel delivery unit and fuel gauge sender - Vehicles with 4-cylinder engine (unit injector) — AUDI

AFB AFF AFN AHH AHU AJM AKN ATJ AVG
Note:

Description of function

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20-152
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Baffle housing (outer section)
Secured in place in fuel tank
Cannot be dismantled
Shown without fuel tank for clearer illustration.

Fuel delivery unit
Checking fuel pump (electrical test)
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20-161
Removing and installing
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20-166

Fuel hose
From fuel pump to baffle housing and fuel pump to suction jet pump
Use uncoupling tool T40020 or press release tabs on connection to disconnect from suction jet pump.

Warning
In extreme cases the fuel pipes/hoses or the fuel can reach a temperature of 100C on vehicles with unit injector engine. Allow the fuel to cool down before disconnecting the pipes/hoses - acute danger of scalding.
Wear protective gloves.
Wear protective goggles.

Fuel return pipe
From fuel filter
Note direction of arrow on flange

Fuel supply pipe
Goes to fuel filter
Note direction of arrow on flange

Flange
Cannot be replaced separately
Installation position: note position of arrow => Page
20-175

Connector
For fuel pump and fuel gauge sender -G

Union nut, 60 Nm
Remove and install with spanner 3217

Seal
Renew
When installing, fit seal (dry) in opening in fuel tank

O rings
Always renew
Ensure correctly fitted

Suction jet pump
With return pipe
Connected to inside of flange
Removing and installing
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20-216
Use uncoupling tool T40020 or press release tabs on connection to disconnect

O ring
Always renew

Fuel gauge sender -G
Checking resistance
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20-176
Removing and installing
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20-179

Description of function

The electric fuel pump delivers fuel from the fuel tank baffle housing to the tandem pump located on the engine.

Therefore it is no longer necessary to bleed the fuel system after running the fuel tank empty or after performing repairs on components of the fuel system.

The electric fuel pump also sends a pressurised stream of fuel into two suction jet pumps (entrainment pumps), one at the bottom of the baffle housing and the other in the rear chamber of the tank. The suction jet pumps ensure that the baffle housing is always kept filled with fuel and the rear chamber of the tank is properly drained.