9 - Fuel Injector Balance Test

TOOLS REQUIRED: 

• J34730 Noid Light
• SA9127E Gauge Bar Set
• SA9182E Electronic Fuel Injection Tester

1. On the SOHC (L24), remove air intake tube. Refer to "Air Induction System Removal" procedures in this manual.
2. Before the Fuel Injector Balance Test is started, the electrical connector should be tested using a Noid Lite J34730.
   1. Disconnect electrical connectors at fuel injectors.
   2. Connect a Noid Lite to the female connector.
      Fig 1: Connecting Noid Light

      Courtesy of GENERAL MOTORS CORP.
   3. Crank the engine.
   4. If the Noid Lite does not blink, the electrical problem must be corrected before continuing.
3. Connect Gauge Bar Set SA9127E to fuel test port.
4. Connect the Electronic Fuel Injection Tester SA9182E.
   1. Connect the plug to a fuel injector.
   2. Connect the red clip to the positive battery post.
   3. Connect the black clip to a clean ground.
   4. Check the power light. If it is not on, check the battery connection again.
      Fig 2: Connect The Electronic Fuel Injection Tester

      Courtesy of GENERAL MOTORS CORP.
5. Set the switch on the fuel injector tester to the 50 Pulse - 10 MS setting.
   NOTE: It may be necessary to cycle the key On/Off a minimum of three times (the key must be off thirty seconds) to bleed all air from the system and achieve maximum system pressure.
6. Cycle the ignition key On/Off several times (DO NOT START ENGINE  ) and bleed off all air in the system using the pressure gauge shut-off valve.
7. Turn the ignition to the Off position for ten seconds. After ten seconds, turn ignition key to the On position (DO NOT START ENGINE  ) and record gauge pressure (1st reading  . See Fig 3).
   Fig 3: Fuel Pressure Example Chart

   Courtesy of GENERAL MOTORS CORP.
8. Using the injector tester, pulse the #1 injector.
9. Record pressure at the instant the gauge needle stops moving (2nd reading  . See Fig 3).
10. Repeat steps  6- 9 for the remaining three injectors.
    NOTE: The engine must be started after four cylinders have been tested to prevent flooding or internal damage.
11. Add all the 2nd Readings  together and divide by 4 (this is the 2nd reading Average  . See Fig 3).
12. Subtract Average of 2nd Readings  from each 2nd Reading  to obtain the Difference  . See Fig 3.
13. An injector is faulty if the Difference  is greater than +/-1.5 psi (10 kPa).
14. Check that all fuel injector connectors are connected. Pull back to ensure a positive engagement.
15. Remove fuel gage bar adapter from fuel pressure test port and recap it.
16. Install air intake tube.
17. Start engine and check for leaks.