GM S-Series Pick-ups and SUV's 1994-1999 Repair Guide

Fuel Pressure Relief

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1994-96 models

Prior to servicing any component of the fuel injection system, the fuel pressure must be relieved. If fuel pressure is not relieved, serious injury could result.

A valve is provided on these fuel systems in order to conveniently test or release the fuel system pressure. A fuel pressure gauge and adapter will be necessary to connect to the fitting. The 2.2L system is equipped with a valve located on the fuel feed inlet fitting, on the opposite end of the lower intake from the pressure regulator.

  1. Disconnect the negative battery cable to assure the prevention of fuel spillage if the ignition switch is accidentally turned ON while a fitting is still disconnected.
  2.  
  3. Loosen the fuel filter cap to release the fuel tank pressure.
  4.  
  5. Make sure the release valve on the fuel gauge is closed, then connect the fuel gauge to the pressure fitting located on the inlet fuel pipe fitting.
  6.  

When connecting the gauge to the fitting, be sure to wrap a rag around the fitting to avoid spillage. After repairs, place the rag in an approved container.

  1. Install the bleed hose portion of the fuel gauge assembly into an approved container, then open the gauge release valve and bleed the fuel pressure from the system.
  2.  
  3. When the gauge is removed, be sure to open the bleed valve and drain all fuel from the gauge assembly.
  4.  

1997 models

  1. Loosen the fuel filler cap.
  2.  
  3. Raise the vehicle and support it with jackstands.
  4.  
  5. Unplug the fuel pump electrical connection and lower the vehicle.
  6.  
  7. Start the engine and let it run until it stalls, then try to start the engine again once or twice to make sure that all the fuel supply and pressure has been depleted.
  8.  
  9. Raise the vehicle and support it with jackstands.
  10.  
  11. Attach the fuel pump electrical connection and lower the vehicle.
  12.  
  13. Tighten the fuel filler cap.
  14.  
  15. Disconnect the negative battery cable to avoid any possible fuel discharge in case somebody accidentally attempts to start the engine.
  16.  
  17. After all necessary repairs have been performed you must reset the system as follows:
    1. Make sure the negative battery cable has been disconnected for more than 10 seconds, then attach the cable to the battery.
    2.  
    3. Turn the ignition ON engine OFF for 5 seconds.
    4.  
    5. Turn the ignition OFF for 10 seconds. The fuel system should now be fully charged.
    6.  

  18.  

1998 models

See Figures 1 and 2



Click image to see an enlarged view

Fig. Fig. 1: On later models vehicles, the fuel pump relay is located in the glove box under a cover



Click image to see an enlarged view

Fig. Fig. 2: Remove the cover to access the relay

  1. Remove the fuel pump relay as follows:
    1. Open the glove box door to access the relay cover.
    2.  
    3. Unfasten the relay cover screw (if equipped) and remove the cover.
    4.  
    5. Grasp the relay and gently pull it to remove it.
    6.  

  2.  
  3. Start the engine and let it run until it stalls, then try to start the engine again once or twice to make sure that all the fuel supply and pressure has been depleted.
  4.  
  5. Reinstall the relay and its cover.
  6.  
  7. Disconnect the negative battery cable to avoid any possible fuel discharge in case somebody accidentally attempts to start the engine.
  8.  

1999-99 models

See Figure 3



Click image to see an enlarged view

Fig. Fig. 3: Attach a suitable fuel pressure gauge to the fuel pressure connection

  1. Disconnect the negative battery cable and make sure the ignition key is in the OFF position.
  2.  
  3. Loosen the fuel filler cap.
  4.  
  5. Attach fuel pressure gauge J 34730-1A or its equivalent to the fuel pressure connection.
  6.  

When connecting the gauge to the fitting, be sure to wrap a rag around the fitting to avoid spillage. After repairs, place the rag in an approved container.

  1. Install the bleed hose portion of the fuel gauge assembly into an approved container, then open the gauge release valve and bleed the fuel pressure from the system.
  2.  
  3. When the gauge is removed, be sure to open the bleed valve and drain all fuel from the gauge assembly.
  4.  

 
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