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Home >> Saturn >> 2002 >> SC2 Automatic, MP6 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Testing & Engine Component Testing >> Fuel Systems (Gasoline) >> Fuel Injector Balance Test (Except SATURN) >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article. After performing Diagnostic System Check - Engine Controls, go to next step.
  2. If fuel injector coil test has been performed, go to next step. If fuel injector coil test has not been performed, perform fuel injector coil test. See FUEL INJECTOR COIL TEST .
    3. NOTE: DO NOT perform this test if the Engine Coolant Temperature (ECT) is above 201°F (94°C).
  3. Observe the ECT parameter on the scan tool. Does the scan tool indicate that the ECT parameter is less than 201°F (94°C)? If yes, go to next step. If no, allow engine to cool below 201°F (94°C), then go to next step.
    4. NOTE: Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic.
  4. Turn OFF the ignition. Turn OFF all accessories. Install the fuel pressure gauge. Turn ON the ignition, with the engine OFF. Command the fuel pump ON with a scan tool. The fuel pump may need to be commanded ON a few times in order to obtain the highest possible fuel pressure. DO NOT start the engine. Observe the fuel pressure gauge, with the fuel pump commanded ON. Is the fuel pressure within the specified value? See FUEL PRESSURE SPECIFICATIONS (EXCEPT SATURN)  table or FUEL PRESSURE SPECIFICATIONS (SATURN)  table. If yes, go to next step. If no, see appropriate FUEL SYSTEM PRESSURE TEST article under BASIC FUEL SYSTEM CHECKS in BASIC DIAGNOSTIC PROCEDURES - CARS - EXCEPT PRIZM article.
    5. NOTE: The fuel pressure may vary slightly when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant.
  5. Monitor the fuel pressure gauge for 1 minute. Does the fuel pressure decrease by more than 5 psi? If yes, see appropriate FUEL SYSTEM PRESSURE TEST article under BASIC FUEL SYSTEM CHECKS in BASIC DIAGNOSTIC PROCEDURES - CARS - EXCEPT PRIZM article. If no, go to next step.
  6. With a scan tool, select the Fuel Injector Balance Test function, within the Special Functions menu. Select an injector to be tested. Press Enter. This will prime the fuel system. Record the fuel pressure indicated by the fuel pressure gauge after the fuel pressure stabilizes. This is the 1st pressure reading. Record the fuel pressure value immediately after the fuel injector stops pulsing. The fuel pressure may rise after the fuel injector stops pulsing. DO NOT record the higher fuel pressure value. Energize the fuel injector by depressing the Pulse Injector button on the scan tool. This will energize the injector and decrease the fuel pressure. Record the fuel pressure indicated by the fuel pressure gauge after the fuel injector has stopped pulsing. This is the 2nd pressure reading. Press Enter again to bring you back to the Select Injector screen. Repeat for each fuel injector. Subtract the 2nd pressure reading from the 1st pressure reading for one fuel injector. The result is the pressure drop value. Obtain a pressure drop value for each fuel injector. Add all of the individual pressure drop values. This is the total pressure drop. Divide the total pressure drop by the number of fuel injectors. This is the average pressure drop. Does any fuel injector have a pressure drop value that is either higher than the average pressure drop or lower than the average pressure drop by 1.5 psi? If yes, go to next step. If no, see appropriate TROUBLE SHOOTING - NO CODES article.
  7. Replace the affected fuel injectors. After repairs, go to next step.
  8. Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, see appropriate TROUBLE SHOOTING - NO CODES article.
FUEL PRESSURE SPECIFICATIONS (EXCEPT SATURN)

Application (1) psi (kg/cm2 )
2.2L & 2.4L 53-59 (3.8-4.2)
3.1L & 3.4L 52-59 (3.7-4.2)
3.5L, 4.0L & 4.6L 41-47 (2.9-3.3)
3.8L
Camaro & Firebird 48-54 (3.4-3.8)
Bonneville, Grand Prix, Park Avenue & Regal 48-55 (3.4-3.9)
All Others 52-59 (3.7-4.2)
5.7L 55-62 (3.9-4.4)
(1) Specification listed is with ignition on and engine off.
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