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Home >> Cadillac >> 2002 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 341 (Engine Controls - System & Component Testing - 3.4L) >> Fuel Systems >> Fuel Injector Balance Test With Special Tool >> Diagnostic Procedures
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Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, 2003 Chevrolet Monte Carlo, and 2003 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. After performing diagnostic system check - engine controls, go to next step.
  2. Did you perform the Fuel Injector Coil Test? If yes, go to next step. If no, perform fuel injector coil test. Go to 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 ignition switch to OFF position. Install the Fuel Pressure Gauge (J 34730-1A) and the fuel pressure gauge fitting. Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON using a scan tool. You may need to command the fuel pump ON a few times, 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 52-59 psi (358-405 kPa)? If yes, go to next step. If no, go to FUEL SYSTEM DIAGNOSIS .
    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 one minute. Does the fuel pressure decrease by more than 5 psi (34 kPa)? If yes, go to FUEL SYSTEM DIAGNOSIS . If no, go to next step.
  6. Connect the Fuel Injector Coil/Balancer Tester (J 39021), Injector Selector Switch box (J 39021-210), and Fuel Injector Test Harness (J 39021-410, or equivalents to the fuel injector multi-way harness connector. Set the amperage supply selector switch on the fuel injector tester to the BALANCE TEST 0.5-2.5 AMP position. Command the fuel pump ON and then OFF using a scan tool. Record the fuel pressure indicated by the fuel pressure gauge after the fuel pressure stabilizes. This is the first 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 PUSH TO START TEST button on the fuel injector tester. Record the fuel pressure indicated by the fuel pressure gauge. This is the second fuel pressure reading. Repeat procedure for each fuel injector. Subtract the second pressure reading from the first 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 more than the average pressure drop or less than the average pressure drop by 1.5 psi (10 kPa)? If yes, go to next step. If no, go to SYMPTOM DIAGNOSIS - ENGINE CONTROLS under SYMPTOMS in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
  7. Clean the fuel injectors. Go to FUEL INJECTOR CLEANING . After cleaning, go to next step.
  8. Operate the vehicle to verify the repair. Does a driveability condition still exist? If yes, go to SYMPTOM DIAGNOSIS - ENGINE CONTROLS under SYMPTOMS in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. If no, system is okay at this time.
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