Diagnostic Procedure

Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.
Did you perform the Fuel Injector Coil Test? If yes, go to next step. If no, go to FUEL INJECTOR COIL TEST .

NOTE: Do not perform this test if the engine coolant temperature is above 201°F (94°C).

Observe the ECT Sensor parameter using a scan tool. Is the ECT Sensor parameter less than 201°F (94°C)? If yes, go to next step.

NOTE: Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic.

Turn ignition switch to OFF position. Turn all accessories OFF. Connect Fuel Pressure Gauge (J 34730-1A), or equivalent, to the fuel pressure connection, located on the fuel rail. See Figure. Turn ignition switch to RUN position, engine OFF. The fuel pump relay may need to be commanded ON a few times to obtain the highest possible fuel pressure. Do not start the engine. Command the fuel pump relay ON using the scan tool. Observe the fuel pressure gauge, with the fuel pump operating. Is the fuel pressure 50-60 psi (345-414 kPa)? If yes, go to next step. If no, go to FUEL SYSTEM DIAGNOSIS (GASOLINE) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.

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.

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 (GASOLINE) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article. If no, go to next step.
Using 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 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 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 second 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. Is the difference between any individual pressure drop and the average pressure drop more than 1.5 psi (10 kPa)? If yes, go to next step. If no, go to SYMPTOM DIAGNOSIS in TROUBLE SHOOTING - NO CODES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.
Replace the affected fuel injectors. After repair, go to next step.
Operate the system to verify the repair. Did you correct the condition? If yes, system is okay at this time. If no, go to SYMPTOM DIAGNOSIS in TROUBLE SHOOTING - NO CODES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.