Diagnostic Procedure

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.
Did you perform the fuel injector coil test? If yes, go to next step. If no, go to FUEL INJECTOR COIL TEST .

CAUTION: Do not perform this test if the ECT is above 201°F (94°C).

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

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

Turn ignition switch to OFF position. Turn all accessories OFF. Install the Fuel Pressure Gauge (J 34730-1A), or equivalent, to 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 no, go to next step. If no, go to FUEL SYSTEM DIAGNOSIS .

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.

Observe the fuel pressure gauge for one minute. Does the fuel pressure drop more than 5 psi (34 kPa)? If yes, go to FUEL SYSTEM DIAGNOSIS . If no, go to next step.

NOTE: It may be necessary to cycle the key ON/OFF a minimum of three times (the key must be in OFF position for 30 seconds) to bleed all air from the system and achieve maximum system pressure.

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 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 either higher than the average pressure drop or lower 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.
Clean the fuel injectors. Go to FUEL INJECTOR CLEANING . After cleaning, go to next step.
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.