Fuel is extremely flammable, so extra precautions must be taken when working on any part of the fuel system. Do not smoke, do not allow open flames or lamps without a ceiling to appear near the working area. Also, do not work in a garage that uses natural gas equipment with a wick.
Fuel pump (carbureted engines)
1. Disconnect the negative battery cable. Disconnect both hoses from the pump and unscrew and remove the two fixing nuts.
2. Carefully remove the fuel pump from the cylinder head. If it sticks, then you can lightly hit a thick spacer with a wooden block.
3. Remove two thin spacers.
4. The fuel pump is sealed and internal components cannot be replaced. In the event of an internal failure, the pump is replaced.
5. Installation is the reverse of removal, however, replace the shims on both sides of the spacer. and tighten evenly to the specified Table of sizes and adjustment data at the end of the Manual by tightening the nuts. Under no circumstances change the thickness of the spacer, otherwise the operation of the pump will be impaired.
Fuel pump (injection engines)
On late models with Motronic, the fuel pump is located inside the fuel tank or next to the fuel tank on models with L-Jetronic. Early models are also equipped with an intermediate pump located in the fuel tank. The intermediate pump feeds the more powerful main pump, which provides the high pressure required for proper fuel system operation.
On early models, the fuel level sensor is located in the fuel tank along with the intermediate pump, and on later models, together with the main fuel pump.
1. Depressurize the fuel system (see Section Relieving pressure in the fuel injection system) and to relieve pressure in the fuel tank, unscrew the filler cap.
2. Disconnect the negative battery cable.
If your vehicle's radio is equipped with an anti-theft system, make sure you know the correct activation code before disconnecting the battery. Before disconnecting the wire, refer to Section Anti-theft audio system and instrument panel language.
If a message in a different language appears on the instrument panel display after connecting the battery, refer to Section Anti-theft audio system and instrument panel language.
External fuel pump
1. Raise the vehicle and place it on stands.
2. Remove the two rubber boots (indicated by arrows), protecting the fuel pump connectors and disconnect the cables from the pump.
3. Using hose clamps, pinch the fuel hoses on both sides of the fuel pump. If there are no clamps, wrap the hoses with rags and clamp them with self-locking pliers, tightening them enough to stop the fuel flow.
4. Disconnect from the fuel pump hoses.
5. Remove the fuel pump mounting screws and remove the pump from under the vehicle.
6. Installation is reverse to the removal procedure.
In-tank fuel or intermediate pump
On some models, access to the fuel pump is provided by removing the rear seat. On other models, access is achieved by removing the floor mat in the luggage compartment.
1. Loosen the fuel pump cover screws (indicated by arrows) and remove the cover from the floor of the car (on some models the fuel pump is located under the rear seat, on others in the luggage compartment).
2. Remove the cover.
3. Locate the fuel pump electrical connectors (1) and fuel level sensor (2) and undock them.
4. To undock the connector, pry up on the bracket to align the tab with the slot and remove the connector from the assembly
5. Also disconnect the inlet and outlet fuel lines.
6. On models with a lock, use two screwdrivers to pry the assembly out from under the tabs
7. On models with nuts to remove the assembly from the fuel tank, unscrew the nuts (indicated by arrows)
8. On late Motronic models, first remove the fuel level sensor...
...then pull the fuel pump straight up from the bottom of the tank (hold all fuel lines together)
General view of the fuel pump assembly on late Motronic systems.
9. On early models, remove the intermediate pump mounting screws and clamps and separate the pump from the assembly.
10. Installation is reverse to removal. If the gasket between the fuel pump and fuel tank is dry, cracked, or damaged, replace it.
Check of functioning and replacement of the gauge of level of fuel
1. Remove the main fuel pump or intermediate pump (as described above) along with the fuel level sensor.
2. Connect an ohmmeter to the contacts and check the correct resistance.
3. For L-Jetronic and early Motronic systems, refer to the table below.
4. In the case of late models of Motronic systems, connect an ohmmeter to the contacts of the fuel level sensor corresponding to contacts 1 and 3 of the electrical connector. As the plunger rises, the resistance should decrease.
L-Jetronic systems and early Motronic
Contact | float position | Resistance |
G and 31 | Move slowly from the EMTY position (Empty) to FULL position (Full) | |
EMPTY (Empty) FULL (Full) | Resistance slowly drops | |
W and 31 | EMPTY (Empty) (Low Fuel Warning) | 3.2±0.7 ohm 71.7±2.3 ohm Infinity |
5. If the resistance values are incorrect, replace the sensor.
6. Installation is reverse to removal.