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

Fuel Injectors

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REMOVAL & INSTALLATION



See Figures 1 and 2

  1. Disconnect the negative battery cable.
  2.  
  3. Relieve the fuel system pressure. Refer to the fuel system relief procedure in this section.
  4.  
  5. Unplug the fuel meter body electrical connection and the fuel feed and return hoses from the engine fuel pipes.
  6.  
  7. Remove the upper intake manifold assembly.
  8.  



Click image to see an enlarged view

Fig. Fig. 1: Exploded view of the fuel meter body assembly

  1. Tag and remove the poppet nozzle out of the casting socket.
  2.  
  3. Remove the fuel meter body by releasing the locktabs.
  4.  

Each injector is calibrated. When replacing the fuel injectors, be sure to replace it with the correct injector.

  1. Disassemble the lower hold-down plate and nuts.
  2.  
  3. While pulling the poppet nozzle tube downward, push with a small screwdriver down between the injector terminals and remove the injectors.
  4.  



Click image to see an enlarged view

Fig. Fig. 2: Exploded view of the fuel injector assembly

To install:
  1. Lubricate the new injector O-rings with clean engine oil, then install the O-rings on the injector assembly.
  2.  
  3. Assenble the CSFI injector assembly into the fuel meter body injector socket.
  4.  
  5. Assemble the lower hold-down plate and nuts. Tighten the nuts to 27 inch lbs. (3 Nm).
  6.  
  7. Install the fuel meter body assembly into the intake manifold and tighten the fuel meter bracket retainer bolts to 88 inch. lbs. (10 Nm).
  8.  


CAUTION
To reduce the risk of fire or injury ensure that the poppet nozzles are properly seated and locked in their casting sockets

  1. Install the fuel meter body into the bracket and lock all the tabs in place.
  2.  
  3. Install the poppet nozzles into the casting sockets.
  4.  
  5. Engage the electrical connections and install new o-ring seals on the fuel return and feed hoses.
  6.  
  7. Install the fuel feed and return hoses and tighten the fuel pipe nuts to 22 ft. lbs. (30 Nm).
  8.  
  9. Connect the negative battery cable.
  10.  
  11. Turn the ignition ON for 2 seconds and then turn it OFF for 10 seconds. Again turn the ignition ON and check for leaks.
  12.  
  13. Install the upper intake manifold.
  14.  

TESTING



See Figure 3

This test requires the use of fuel injector tester J 39021 or its equivalent.

  1. Disconnect the fuel injector harness and attach a noid light in order to test for injector pulse.
  2.  
  3. With the engine cool and the ignition turned OFF , install the fuel pressure gauge to the fuel pressure connection. Wrap a shop towel around the fitting while connecting the gauge to prevent spillage.
  4.  
  5. Turn ON the ignition and record the fuel gauge pressure with the pump running.
  6.  
  7. Turn OFF the ignition. Pressure should drop and hold steady at this point.
  8.  
  9. To perform this test, set the selector switch to the balance test 2.5 amp position.
  10.  
  11. Turn the injector ON by depressing the button on the injector tester. Note this pressure reading the instant the gauge needle stops.
  12.  
  13. Repeat the balance test on the remaining injectors and record the pressure drop on each.
  14.  
  15. Start the engine to clear fuel from the intake. Retest the injectors that appear faulty. Any injector that has a plus or minus 1.5 psi (10 kPa) difference from the other injectors is suspect.
  16.  



Click image to see an enlarged view

Fig. Fig. 3: Fuel injector testers can be purchased or sometimes rented

 
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