Fuel level sensor — removal and installation (Audi 100 C3)

Table of contents: Removal ↓ Installation ↓

Note: When working with fuel system components, follow the precautions given in Chapter 1.

Removal

1. The sensor is mounted on top of the fuel tank and is accessible through a hatch in the trunk floor. The unit sends an alternating voltage signal to the fuel gauge mounted in the instrument panel and is also the connection point for the fuel supply and return hoses.

2. The block is immersed in the fuel tank.

3. Make sure the vehicle is on a level surface, then disconnect the negative battery cable and move it away from the terminal.

4. Remove the trim from the trunk floor. On wagon models, fold the rear seat forward, then remove the row of screws securing the carpet to the floor. Remove the carpet.

5. Unscrew the hatch mounting screws and lift the hatch from the floor.

6. Disconnect the wiring harness connector from the sensor.

7. Wrap a rag around the fuel lines to absorb any spilled fuel, then loosen the clamps and remove the lines from the fittings on the sensor. Note the arrows on the fittings indicating the direction of fuel flow - mark the fuel lines accordingly to ensure proper installation. Also note the location of the unit in the fuel tank.

8. Unscrew the plastic mounting ring and lift the sensor, holding it for a while above the fuel level in the tank until the excess fuel drains from it.

9. Remove the sensor, place it on a piece of cardboard or rag. Inspect the float at the end of the lever - replace the sensor if it appears damaged.

10. The fuel pickup tube in the sensor is spring loaded. Make sure that the pickup tube moves freely under the tension of the spring relative to the sensor body.

11. Remove the rubber seal from the hole in the fuel tank, inspect it and replace it if necessary.

12. Inspect the sensor runner and conductor; wash them from dirt and inspect for breaks in the conductor. The electrical specification for the sensor is not specified by Audi, but the integrity of the runner and conductor can be checked by connecting a multimeter (in resistance measurement mode) across the sensor connector terminals. The resistance should change as the float arm moves up and down; if there is an open circuit, the sensor is faulty and should be replaced.