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how do i change the fuel pump on a 1990 cadillac sedan deville


The fuel pump is

Print

The fuel pump is a high-pressure electric pump mounted in the fuel tank. The impeller serves as a vapor separator and precharges the high-pressure assembly. Fuel is pumped at a positive pressure through an in-line fuel filter to the fuel rail assembly. A pressure regulator maintains a preset pressure in the fuel line to the injectors. Excess fuel is returned to the fuel tank through the fuel return line. The electric fuel pump is connected in parallel to the PCM and is activated by the PCM when the ignition is turned on and the engine is cranking or operating. If the engine stalls or if the starter is not engaged, the fuel pumps will stop in about one second.

REMOVAL & INSTALLATION



3.0L Engine



Click image to see an enlarged view

Fig. The modular sender contains the pump, float, and reservoir



NOTE
The special tool J 42219 Fuel Tank Sender Wrench is needed to perform this repair.


The electric fuel pump is a turbine pump located inside the modular fuel sender. The electric fuel pump operation is controlled by the PCM through the fuel pump relay.

  1. Properly relieve the fuel system pressure.
  2.  
  3. Raise and safely support the vehicle securely.
  4.  
  5. Disconnect the negative battery cable.
  6.  
  7. Drain the fuel tank.

  8.  
  9. Remove the fuel tank.
  10.  
  11. Remove the spring-loaded clamp around the fuel tank boot.
  12.  
  13. Remove the fuel tank sending unit wiring harness.

  14.  
  15. Remove the fuel sender assembly.
  16.  
  17. Remove the fuel sending unit seal (lip) from the fuel sending unit cover.

    1. Slide downward, past the reservoir, and carefully over the float arm assembly.
    2.  


  18.  
  19. Loosen the clamps and remove the fuel feed or return hose.

    1. Before removing the fuel return hose from the reservoir, disconnect the check valve assembly from the reservoir to prevent damage to the reservoir or check valve.
    2.  


  20.  
  21. Remove the fuel level sensor electrical connector.
  22.  
  23. Remove the fuel level sensor by removing the screws.
  24.  
  25. Loosen the clamp and remove the fuel feed hose from the fuel pump.
  26.  
  27. Remove the fuel pump electrical connectors.
  28.  
  29. Remove the fuel pump damper ring.
  30.  
  31. Remove the fuel pump.
  32.  


To install:



NOTE
Always install a new strainer when replacing the fuel pump.



  1. Install the fuel pump strainer.
  2.  
  3. Install the fuel pump bracket.
  4.  
  5. Install the fuel pump.
  6.  
  7. Install the fuel pump damper ring.
  8.  
  9. Install the fuel pump electrical connectors.

  10.  
  11. Install the fuel feed hoses to the fuel pump and secure.
  12.  
  13. Install the fuel level sensor and the attaching screws.
  14.  
  15. Install the fuel level sensor electrical connectors.

  16.  
  17. Install the fuel sending unit seal (lip) to the fuel sending unit cover.
  18.  
  19. Install the fuel sender assembly.
  20.  
  21. Install the fuel tank.
  22.  
  23. Lower the vehicle.
  24.  
  25. Refill the fuel tank.
  26.  
  27. Connect the negative battery cable.
  28.  
  29. Crank the engine for a few seconds (if the engine starts, turn it off) and then check for fuel leaks.

  30.  


4.5L and 4.9L Engine

  1. Disconnect the negative battery cable.
  2.  
  3. Relieve the fuel system pressure.
  4.  
  5. Raise and safely support the vehicle with jackstands.
  6.  
  7. Safely drain and remove the fuel tank assembly.
  8.  
  9. Turn the fuel pump cam lock ring counterclockwise and lift the assembly out of the tank.
  10.  
  11. Remove the fuel pump from the level sensor unit as follows:

    1. Pull the pump up into the attaching hose or pulsator while pulling outward away from the bottom support.
    2.  
    3. Take care to prevent damage to the rubber insulator and strainer during removal.
    4.  
    5. When the pump assembly is clear of the bottom support, pull the pump out of the rubber connector for removal.
    6.  


  12.  


To install:

  1. Replace any attaching hoses or rubber sound insulator that show signs of deterioration.
  2.  
  3. Push the fuel pump into the attaching hoses and install the pump/sensor assembly into the tank. Always use a new O-ring seal. Be careful not to fold over or twist the strainer when installing the sensor unit. Also, make sure the strainer does not block full travel of the float arm.
  4.  
  5. Install the cam lock and turn clockwise to lock.
  6.  
  7. Install the fuel tank.
  8.  
  9. Fill the tank with four gallons of gas and check for fuel leaks.

  10.  





Click image to see an enlarged view

Fig. Sending unit installation-except 1993-98 Eldorado and Seville




Click image to see an enlarged view

Fig. Fuel sender assembly-except 1993-98 Eldorado and Seville

4.6L Engine

The fuel pump used in this system is part of the fuel sender assembly.

Special tools needed for the repair. J 34730-1A or equivalent, fuel pressure gauge. J 39765 Fuel sender lock nut wrench, or equivalent.



NOTE
Do not handle the fuel sender assembly by the fuel pipes. The amount of leverage generated by handling the fuel pipes could damage the joints.




CAUTION

Drain the fuel tank to no more than
3
/
4
of a tank before removing the fuel sender retaining ring or fuel sender access panel in order to avoid possible fuel spillage.




NOTE
Always replace the fuel sender O-ring when reinstalling the fuel sender assembly.



  1. Relieve the fuel system fuel pressure.
  2.  
  3. Disconnect the negative battery cable.

  4.  
  5. Determine if the fuel tank must be dropped to access the pump/sender, or if it is accessible through the rear compartment. If it is accessible through the rear compartment, use the following procedure.
  6.  

  7. Drain the fuel tank to at least
    3
    /
    4

    of a tank, if full.

  8.  
  9. If it is not accessible, safely drain and remove the fuel tank.
  10.  
  11. Remove the spare tire cover, the jack, and the spare tire.
  12.  




NOTE
Remove the rear compartment floor trim to avoid damage from fuel spillage.



  1. Remove the rear compartment floor trim.
  2.  
  3. Remove the bolts from the fuel sender access panel.

  4.  
  5. Detach the quick-connect fittings at the fuel sender assembly.
  6.  
  7. Detach the electrical connector at the modular fuel sender.
  8.  
  9. Detach the electrical connector at the fuel tank pressure sensor.
  10.  
  11. Remove the fuel sender retaining ring using the J 39765 (or equivalent) Fuel Sender Spanner Wrench.
  12.  




NOTE
When removing the modular fuel sender assembly from the fuel tank, the reservoir bucket on the fuel sender assembly must be tipped slightly during removal in order to avoid damage to the float. Place any remaining fuel into an approved container once the modular fuel sender assembly is removed from the fuel tank.




WARNING
The modular fuel sender assembly will spring-up when the locking ring is removed.



  1. Pull the modular fuel sender straight up while pumping the fuel from the reservoir.
  2.  
  3. Clean and inspect the fuel sender assembly O-ring sealing surfaces.
  4.  


To install:

  1. Position the new fuel sender assembly O-ring on the fuel tank.
  2.  




NOTE

Care should be taken not to fold over or twist the fuel pump strainer when installing the fuel sender assembly, as this will restrict fuel flow.



  1. Ensure that the fuel pump strainer does not block full travel of the float arm.
  2.  
  3. Reinstall the fuel sender assembly and the fuel sender assembly retainer cam using the Fuel sender spanner wrench.
  4.  
  5. Install the quick-connect fittings at the fuel sender assembly.

  6.  
  7. Attach the electrical connector at the fuel tank pressure sensor.
  8.  
  9. Attach the electrical connector at the fuel sender assembly.
  10.  
  11. Connect the negative battery cable.
  12.  
  13. Inspect for leaks.


    1. Turn the ignition switch
      ON
      for 2 seconds.
    2.  

    3. Turn the ignition switch
      OFF
      for 10 seconds.

    4.  

    5. Turn the ignition switch
      ON
      and check for leaks.

    6.  


  14.  
  15. Reinstall the fuel access panel, and tighten the fuel sender access panel bolts to 18 inch lbs. (2 Nm).
  16.  
  17. Reinstall the rear compartment floor trim.
  18.  
  19. Reinstall the spare tire, the jack, and the spare tire cover.
  20.  
  21. Add fuel and reinstall the fuel tank filler pipe cap.
  22.  





Click image to see an enlarged view

Fig. Diagram of a modular fuel sender depicting the typical fuel flow

TESTING



3.0L Engine

The special tool required to perform these tests is J 34730-91 Fuel Pressure gauge or equivalent.

Except 3.0L Engine

When the ignition switch is turned
ON
, the PCM will turn
ON

the in-tank fuel pump. The fuel pump is located inside the modular fuel sender. The fuel pump is not serviceable separate from the sender. The in-tank fuel pump will remain
ON
as long as long as the t engine is cranking or running and the PCM is receiving reference pulses. If there are no reference pulses. The PCM will turn the in-tank fuel pump
OFF
2 seconds after the ignition switch is turned
ON
or 2 seconds after the engine stops running.




Click image to see an enlarged view

Fig. Diagram of a typical fuel system pressure test


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