Examination
1. Check the fuses. If they are serviceable, then check if the fuel pump works when the engine is started.
2. Ask an assistant to turn on the ignition. Listen to see if the fuel pump kicks in. If you hear the noise of the running fuel pump, then check if it supplies fuel.
3. Four-cylinder engines with Mono-Motronic fuel injection. Disconnect the fuel supply line at the junction with the high pressure fuel lines of the injectors.
4. Put a hose on the released end of the fuel supply line and lower it into a container.
5. Ask the assistant to work as a starter. Fuel must flow through the system.
6. Four-cylinder engines with Digifant injection system. Disconnect the fuel supply line from the distribution line.
7. Put a hose on the released end of the fuel supply line and lower it into a container.
8. Ask the assistant to work as a starter. Fuel must flow through the system.
9. Five-cylinder engines with KE-III-Jetronic fuel injection system. Disconnect the fuel supply line. Have a rag ready in case of a fuel leak. Fuel must also flow out when the engine is turned off, because the pressure in the system is maintained by the functioning of the hydraulic accumulator. If no fuel comes out, have an assistant run the starter (see illustration).
10. Six-cylinder engine with MP1/MPFI fuel injection. Disconnect the fuel supply line from the distribution line and also put a hose on the fuel supply line, lower the free horses of which into a container.
11 All engines. Check the multi-pin plug on the fuel pump connection flange and make sure the fuel pump motor is receiving power. To do this, unscrew the trunk floor cover and unscrew the bolts securing the black cover to the bottom.
12. Disconnect the multi-pin plug.
13. Connect a voltmeter or a tester with a control diode bulb to the pins of the plug 1 and 4 (brown and green-yellow wires) and check that the motor is receiving 12 volts. Have an assistant run the starter to check for voltage. The shift lever must be in neutral and the parking brake must be applied. If the power supply to the pump is normal, but it does not work, then the pump is faulty and must be replaced. If there is no power, check the fuel pump relay on the central distribution panel. Other causes of fuel pump failure may include:
- breakage of the power supply wire to the relay or fuel pump;
- clogged or kinked fuel line;
- clogged filter or accumulator.
Withdrawal
The removal of the fuel pump must be carried out by a workshop, because the pump is removed together with the inner part of the lower casing. The fuel pump is disconnected from the lower casing using a special key 3307. If the specified key is available, then follow these steps to remove the fuel pump.
1. Disconnect the multi-pin plug.
2. Squeeze the leashes of the fuel return line connectors and disconnect it (see illustration 2.4).
3. Disconnect the supply hose.
4. Loosen the plastic union nut. Usually this nut is tightened tightly and turns away with difficulty. It is recommended in such cases to install a screwdriver on the face of the nut and, by hitting the handle of the screwdriver with a hammer, loosen the nut.
5. Remove the connecting flange of the fuel and external tank by pulling it up. If necessary, disconnect the fuel return pipe connecting pipe from the back of the flange by squeezing its leashes.
6. Disconnect the fuel gauge sensor plug.
7. Put the special key 3307 on the inside of the lower housing of the fuel pump and turn the key to the left until it stops (see illustration).
8. Remove the fuel pump along with the inside of the lower housing and the connecting flange.
9. Mark the mounting position of the fuel pump, hoses, power wires and wire attachment points in order to then install them in their original place.
10. Mark the installation position of the fuel pressure line.
11. Disconnect the fuel pressure line and remove the pump from the inside of the lower housing. Depending on the type of fuel pump, this procedure is performed differently.
12. Fuel pump 60 mm. Turn the sieve at the bottom of the inner part to the left side and remove the pump. When installing, the lug on the pump housing must fit into the groove on the inside of the lower housing. Don't forget to install the O-ring. 1
13. Fuel pump 40 mm. Squeeze together the retaining brackets on the inside of the lower housing and remove the pump. Subsequent installation of the pump is only possible in one position.
Attention! When installing the fuel pump for AUDI 80 front-wheel drive vehicles, its reference mark must match the single notch on the inside of the lower housing. For quattro models, the pump reference mark is set against the double notch on the inside of the lower housing (see illustrations).
14. Screw the inner part into the lower case with the key 3307 and connect all the removed elements.
Attention! When installing the connecting flange, the arrow on the flange must be opposite the mark on the fuel tank.
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