Fuel Supply System, Function

1998 Audi A8 Sedan (4D2) V8-3.7L (AEW)SECTION Fuel Supply System, Function








The fuel tank employs a multi-chamber system.

The dual-stage electric fuel pump is located in a baffle housing (not shown in illustration).

The first stage of the fuel pump produces a stream of fuel (large arrow in illustration) which is directed to the three suction jet pumps -2-, -3- and -5-, where it is passed through a nozzle and thus accelerated.

The accelerated jet of fuel draws off the surrounding fuel in the individual chambers and delivers it to the adapter plate -1- in the baffle housing via a system of pipes.

The second stage of the electric fuel pump delivers the fuel from the baffle housing to the engine.

The first stage of the electric fuel pump, the system of suction jet pumps and the baffle housing together form a closed circuit inside the fuel tank.

For reliable starting, there must be fuel in the baffle housing at all times. To ensure that this is the case, even when an empty tank is topped up with a small quantity of fuel, the fuel filler pipe -4- goes directly into the adapter plate -1- on the baffle housing. In this way the fuel is always supplied directly to the fuel delivery module.

RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.