Chevrolet Blazer/Jimmy 1969-1982 Repair Guide

Injection Nozzles (Injectors)

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REMOVAL



  1. Disconnect the batteries.
  2.  
  3. Disconnect the fuel line clip and remove the fuel return hose.
  4.  
  5. Remove the fuel injection line.
  6.  
  7. Remove the injection nozzle using the special tool if possible. If not, use a 30mm open end wrench. Be sure to remove the nozzle using the large 30mm hex nut. Failure to do this will result in damage to the injection nozzle. Always cap the nozzle and lines to prevent damage and contamination.
  8.  

TESTING



If all of the following tests are satisfied, the nozzle holder can be installed in the engine without any changes. If any one of the tests is not satisfied, the complete nozzle holder assembly must be replaced.

PREPARATION



  1. Connect the nozzle holder assembly to the test line.
  2.  
  3. Close the shutoff valve to the pressure gauge.
  4.  
  5. Fill and flush the nozzle holder assembly with test oil by activating the lever repeatedly and briskly. This will apply test oil to all functionally important areas of the nozzle and purge it of air.
  6.  

OBTAINING PRESSURE CHECK



  1. Open shutoff valve at pressure gauge 1 / 4 turn.
  2.  
  3. Depress lever of tester slowly. Note at what pressure the needle of the pressure gauge stopped, indicating an increase in pressure (nozzle does not chatter) or at which pressure the pressure dropped substantially (nozzle chatters). The maximum observed pressure is the opening pressure.
  4.  
  5. The opening pressure should not fall below the lower limit of 1600 psi.
  6.  
  7. Replace nozzles which fall below the lower limit.
  8.  

LEAKAGE TEST



  1. Further open shutoff valve at pressure gauge ( 1 / 2 to 1- 1 / 2 turns).
  2.  
  3. Blow-dry nozzle tip.
  4.  
  5. Install two clear plastic lines (approximately 1-1 1 / 2 inch) over leak-off connections.
  6.  
  7. Depress lever of manual test stand slowly until gauge reads a pressure of 1380 psi. Observe tip of nozzle. A drop may form but not drop off within a period of 10 seconds.
  8.  
  9. Replace the nozzle holder assembly if a droplet drops off the nozzle bottom within the 10 seconds.
  10.  

CHATTER TEST



  1. Close shutoff lever at pressure gauge.
  2.  
  3. Depress lever of manual test stand slowly noting whether chatter noises can be heard.
  4.  
  5. If no chatter is heard, increase the speed of lever movement until it reaches a point where the nozzle chatters.
  6.  
  7. The chatter indicates that the nozzle needle moves freely and that the nozzle seat, guide, as well as the pintle, have no mechanical defects.
  8.  
  9. Replace nozzles which do not chatter.
  10.  

SPRAY PATTERN



  1. Close shutoff valve at pressure gauge.
  2.  
  3. Depress lever of manual test stand downward abruptly and quickly. The spray should have a tight, evenly shaped conical pattern which is well atomized. This pattern should be concentric to the nozzle axis. Streamlike injections indicate a defect.
  4.  

INSTALLATION



  1. Remove protective caps from the nozzle.
  2.  
  3. Install nozzle and torque to 50 ft. lbs.
  4.  
  5. Connect fuel injection line, torque nut to 20 ft. lbs.
  6.  
  7. Install fuel return hose.
  8.  
  9. Install fuel line clip.
  10.  
  11. Connect battery.
  12.  

 
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