GM Corsica/Beretta 1988-1996 Repair Guide

Fuel Pump

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REMOVAL & INSTALLATION



The fuel pump is located in the fuel tank. Removal and installation procedures require the fuel tank to be removed from the vehicle.


CAUTION
The fuel system pressure must be relieved before attempting any service procedures. Use caution to avoid the risk of fire by disposing of any fuel and fuel soaked rags properly.

1988-92 Vehicles

See Figures 1, 2 and 3

  1. Properly relieve the fuel system pressure.
  2.  
  3. If not done already, disconnect the negative battery cable.
  4.  
  5. Using a siphon hose and pump, drain the fuel from the fuel tank into an approved container.
  6.  
  7. Raise and safely support the vehicle.
  8.  
  9. Support the fuel tank securely, then disconnect the retaining straps.
  10.  
  11. Lower the tank enough to disconnect the sending unit wire, the hoses and the ground strap. Remove the fuel tank from the vehicle.
  12.  
  13. Using a locking cam tool, remove the sending unit retaining cam from the fuel tank.
  14.  



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Fig. Fig. 1: A special tool is usually available to remove or install the fuel pump locking cam



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Fig. Fig. 2: Once the locking cam is released it can be removed to free the fuel pump

  1. Remove the fuel pump and sending unit assembly from the tank. Remove and discard the O-ring gasket.
  2.  



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Fig. Fig. 3: Exploded view of the fuel pump and related components - 1988-92 vehicles

To install:
  1. Install a new O-ring and gasket. Carefully install the fuel pump and sending unit assembly into the fuel tank.
  2.  
  3. Install the retaining cam and lock and secure the sending unit in place to the fuel tank.
  4.  
  5. Raise the tank in position to connect the sending unit wire, the hoses and the ground strap. Install the tank retaining straps and secure the tank in place.
  6.  
  7. Carefully lower the vehicle, then refill the tank with fuel.
  8.  
  9. Connect the negative battery cable. Turn the ignition switch to the ON position, to restore system pressure.
  10.  
  11. Start the engine and check for fuel leaks.
  12.  

1993-96 Vehicles

See Figures 4, 5, 6 and 7

  1. Properly relieve the fuel system pressure.
  2.  
  3. If not done already, disconnect the negative battery cable.
  4.  
  5. Using a siphon hose and pump, drain the fuel from the fuel tank into an approved container.
  6.  
  7. Raise and safely support the vehicle.
  8.  
  9. Remove the fuel tank from the vehicle, as outlined later in this section.
  10.  


CAUTION
When removing the modular sender, be careful as the sender may spring up from its position. Also, during removal, the reservoir bucket is full of fuel and must be tipped slightly during removal to avoid damage to the float.

  1. While holding the modular fuel sender assembly down, remove the snapring from the designated slots located on the retainer. Remove and discard the fuel sender O-ring and replace with a new one during installation.
  2.  



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Fig. Fig. 4: Exploded view of the modular fuel sender used on 1993-96 vehicles

  1. Remove the external fuel strainer.
  2.  
  3. Remove Connector Position Assurance (CPA) #8 from the electrical connector, then detach the fuel pump electrical connector.
  4.  
  5. Gently release the tabs on the sides of the fuel sender to the cover assembly. Begin by squeezing the sides of the reservoir and releasing the tab opposite the fuel level sensor. Move clockwise to release the second and third tab using the same procedure.
  6.  



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Fig. Fig. 5: Remove the modular sender cover by squeezing the sides of the reservoir to unlatch the tabs

  1. Lift the cover out far enough to detach the fuel pump electrical connector.
  2.  
  3. Rotate the fuel pump baffle #18 counterclockwise and remove the baffle and pump from retainer #7. Refer to the accompanying illustration for details.
  4.  



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Fig. Fig. 6: Rotate the baffle and pump to remove

  1. Slide the fuel pump outlet out of the slot.
  2.  
  3. Remove the fuel pump outlet seal.
  4.  

To install:
  1. Install the fuel pump outlet seal.
  2.  



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Fig. Fig. 7: Install the fuel pump outlet seal

  1. Slide the fuel pump outlet in the slots of reservoir cover.
  2.  
  3. Install the fuel pump and baffle assembly onto the reservoir retainer #7 and rotate clockwise until seated.
  4.  
  5. Lower retainer assembly #7 partially into the reservoir. Line up all three sleeve tabs. Press the retainer onto the reservoir making sure all three tabs are firmly seated. Gently pull on the fuel pump reservoir retainer to be sure a secure fastening was achieved. If not secure, replace the entire fuel sender.
  6.  
  7. Attach the fuel pump connector.
  8.  
  9. Install CPA #8 to the fuel sender cover #7.
  10.  
  11. Install a new external fuel strainer #14.
  12.  
  13. Install new O-ring on the modular fuel sender to the tank.
  14.  
  15. Align the tab on the front of the sender with the slot on the front of the retainer snapring.
  16.  
  17. Slowly apply pressure to the top of the spring loaded sender, until the sender aligns flush with the retainer on the tank.
  18.  
  19. Insert the snapring into the designated slots. Make sure the snapring is fully seated within the tab slots.
  20.  
  21. Install the fuel tank, as outlined later in this section.
  22.  
  23. Carefully lower the vehicle, then refill the tank with fuel.
  24.  
  25. Connect the negative battery cable. Turn the ignition switch to the ON position, to restore system pressure.
  26.  
  27. Start the engine and check for fuel leaks.
  28.  

TESTING



See Figure 8

When the ignition switch is turned ON , the Electronic Control Module (ECM) will turn ON the in-tank fuel pump. It will remain ON as long as the engine is cranking or running, and the ECM is receiving references pulses. If there are no reference pulses, the ECM will shut OFF the fuel pump within 2 seconds after ignition ON or engine stops.

The pump will deliver fuel to the fuel rail and injectors, then to the pressure regulator, where the system pressure is controlled to about 34-47 psi. Excess fuel is then returned to the fuel tank.

  1. Wrap a towel around the fuel pressure connector to absorb any small amount of fuel leakage that may occur while installing the gauge.
  2.  



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Fig. Fig. 8: Fuel pressure can be checked using an inexpensive pressure/vacuum gauge

  1. The ignition should be off for at least 10 seconds and the air conditioning OFF .
  2.  
  3. With the ignition ON the fuel pump should run for about 2 seconds. The ignition ON fuel pump pressure should be 40.5-47 psi. This pressure is controlled by the spring pressure within the regulator assembly.
  4.  
  5. When the engine is idling, the manifold pressure is low (high vacuum) and is applied to the fuel regulator diaphragm. This will offset the spring and lower the fuel pressure. This idle pressure will vary somewhat depending on the barometric pressure, however the pressure idling should be less indicating pressure regulator control.
  6.  
  7. Pressure that continues to fall is caused by 1 of the following:

    In-tank fuel pump check valve not holding
     
    Pump coupling hose or pulsator leaking
     
    Fuel pressure regulator valve leaking
     
    Injector(s) sticking open
     

  8.  

A injector sticking open can best be determined by checking for a fouled or saturated spark plug(s).

 
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