GM Caprice 1990-1993 Repair Guide

Electric Fuel Pump

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REMOVAL & INSTALLATION




CAUTION
To reduce the risk of fire and personal injury the fuel pressure must be relieved.

  1. Disconnect the negative battery cable and relieve the fuel system pressure.
  2.  
  3. Raise and support the vehicle safely.
  4.  
  5. Remove the fuel tank.
  6.  
  7. Remove the fuel tank sending unit and pump assembly as follows:
    1. On 1990 models, use tool J-24187 or equivalent to remove the assembly retaining cam, assembly and O-ring from fuel tank. Discard the O-ring.
    2.  
    3. On 1991-93 models, remove the assembly attaching nuts, retaining flag, assembly and O-ring from the tank. Discard the O-ring.
    4.  

  8.  

To install:
  1. Install fuel sending unit in fuel tank as follows:
    1. On 1990 models, install a new O-ring on fuel tank. Use tool J-24187, or equivalent, to connect fuel meter assembly and assembly retaining cam and fuel tank.
    2.  
    3. On 1991-93 models, position a new O-ring on fuel tank. Install fuel sender assembly, retaining flag, and attaching nuts to fuel tank. Tighten attaching nuts to 27 inch lbs. (3 Nm).
    4.  

  2.  
  3. Install fuel tank.
  4.  
  5. Lower vehicle.
  6.  
  7. Turn the ignition ON for 2 seconds, OFF for 10 seconds, the ON and inspect the system for leaks.
  8.  

TESTING



For more complete Fuel Injection Testing and Diagnosis, refer to Engine Controls Diagnostic Charts.

When the ignition switch is turned ON , the ECM will turn the in-tank fuel pump ON . It will remain on as long as the engine is cranking or running and the ECM is receiving ignition reference pulses. If there are no reference pulses, the ECM will shut the fuel pump OFF within 2 seconds after the key is turned ON . The pump will deliver fuel to the TBI unit at a pressure controlled by the internal regulator to approximately 9-13 psi. Excess fuel is then returned to the fuel tank.

While the engine is stopped, the fuel pump can be activated by applying battery voltage to the fuel pump test terminal located near the passenger side cowl of the engine compartment.

Fuel pressure should be noted while the fuel pump is running. Fuel pressure will drop immediately after the fuel pump stops running due to the controlled bleed in the fuel system.

  1. Turn the ignition OFF and relieve fuel system pressure by removing fuel filler cap.
  2.  
  3. Locate the engine compartment fuel feed quick-connect fitting. Uncouple the fuel supply flexible hose as follows:
    1. Grasp both ends of the fitting and twist female end 1 / 4 turn in each direction to loosen any dirt in fitting.
    2.  
    3. Wearing proper safety glasses, use compressed air to blow dirt out of the quick-connect fitting.
    4.  

  4.  
  5. Separate the male and female leads of the connector by inserting tool into female end of the connector to release the male end.
  6.  
  7. Install a fuel pressure gauge between the two ends of the connector. Be sure to always lubricate the male end with a few drops of engine oil to ensure proper connection and prevent a fuel leak.
  8.  
  9. Apply battery voltage to the fuel pump test connector.
  10.  
  11. The fuel pressure should be 9-13 psi.
  12.  

 
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