Diagnostic Procedure (With Feedback Fuel System)

WARNING: This page is about a different car, the 2003 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.

Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - 5.7L CORVETTE article.
Did you perform the Fuel Injector Coil Test? If yes, go to next step. If no, see FUEL INJECTOR COIL TEST .

NOTE: DO NOT perform this test if the ECT is above 201°F (94°C). Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic. The fuel pump relay may need to be commanded ON a few times, in order to obtain the highest possible fuel pressure.

Install the fuel pressure gauge. Turn ignition ON, with the engine OFF. Command fuel pump relay ON with a scan tool. Observe fuel pressure gauge, with fuel pump operating. Is fuel pressure within 55-62 psi (380-427 kPa)? If yes, go to next step. If no, see FUEL SYSTEM DIAGNOSIS under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 5.7L CORVETTE article.

NOTE: The fuel pressure will decrease 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 5 minutes. Does the fuel pressure decrease to less than 51 psi (350 kPa)? If yes, see FUEL SYSTEM DIAGNOSIS under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 5.7L CORVETTE article. If no, go to next step.
1. DO NOT repeat any portion of this test before running the engine in order to prevent the engine from flooding. Connect Fuel Injector Tester (J-39021) to a fuel injector.
2. Set amperage supply selector switch on fuel injector tester to Balance Test 0.5-2.5 amp position.
3. Command fuel pump relay ON and OFF with a scan tool.
4. Energize fuel injector by depressing Push to Start Test button on fuel injector tester.
5. Record fuel pressure indicated by fuel pressure gauge after fuel pressure stabilizes. This is the first pressure reading.
6. Record fuel pressure indicated by fuel pressure gauge after fuel injector has stopped pulsing. This is the second fuel pressure reading.
7. Repeat steps A - F for each fuel injector.
8. Subtract the second pressure reading from the first pressure reading for one fuel injector. The result is the pressure drop value.
9. Obtain a pressure drop value for each fuel injector.
10. Add all of the individual pressure drop values. This is the total pressure drop.
11. 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, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - 5.7L CORVETTE article.
Replace affected fuel injector. See FUEL RAIL & INJECTORS under FUEL SYSTEMS in REMOVAL & INSTALLATION - CORVETTE article. After repair is complete, go to next step.
Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - 5.7L CORVETTE article.