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Diagnostic Procedure (With Feedback Fuel System)

NOTE: For terminal and circuit identification, see WIRING DIAGRAMS  .
  1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 5.7L CORVETTE article.
  2. Connect scan tool. Turn ignition on. Using scan tool, command fuel pump relay on and off. If fuel pump turns on and off, check for intermittent problem. See INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 5.7L CORVETTE article. If fuel pump does not turn on and off, go to next step.
  3. Using scan tool, command fuel pump relay on and off. If fuel pump relay clicks, go to step  9 . If fuel pump relay does not click, go to next step.
  4. Turn ignition off. Disconnect fuel pump relay located in underhood fuse block. See Figure . Turn ignition on. Using test light connected to ground, probe fuel pump relay control circuit at relay cavity. Using scan tool, command fuel pump relay on and off. If test light turns on and off, go to next step. If test light does not turn on and off, go to step  6 .
  5. Connect test light between fuel pump relay control circuit and fuel pump relay ground circuit at relay cavities. Using scan tool, command fuel pump relay on and off. If test light turns on and off, go to step  21 If test light does not turn on and off, go to step  25 .
  6. If test light remains illuminated with each command, go to next step. If test light does not illuminate at all, go to step  8 .
  7. Check for short to voltage in fuel pump relay control circuit. Repair as necessary. After repairs, go to step  30 . If circuit is okay, go to step  29 .
  8. Check for open or short to ground in fuel pump relay control circuit. Repair as necessary. After repairs, go to step  30 . If circuit is okay, go to step  22 .
  9. Turn ignition on. If fuel pump runs continuously, go to next step. If fuel pump does not run continuously, go to step  11 .
  10. Turn ignition off. Disconnect fuel pump relay located in underhood fuse block. Turn ignition on. If fuel pump runs continuously, go to step  24 . If fuel pump does not run continuously, go to step  28 .
  11. Check F/PMP fuse (20-amp) located in underhood fuse block. If fuse is open, go to next step. If fuse is okay, go to step  15 .
  12. Remove the left rear wheel house panel. Disconnect the fuel pump harness in-line connector. Test the supply voltage circuit of the fuel pump between the fuel pump relay and the fuel pump harness in-line connector for a short to ground. See Figure . Replace the F/PMP fuse if necessary. After repairs, go to step  30 . If circuit is okay, go to next step.
  13. Remove the left fuel tank. Refer to FUEL TANKS (WITH FEEDBACK FUEL SYSTEM) under FUEL SYSTEMS in REMOVAL & INSTALLATION - CORVETTE article. Inspect the fuel sender harness on top of the fuel tank for damage to the harness or short to ground in the supply voltage circuit of the fuel pump. See Figure . Replace the F/PMP fuse if necessary. After repairs, go to step  30 . If circuit is okay, go to next step.
  14. Install all removed electrical components. Install a new F/PMP fuse. Command the fuel pump relay ON with a scan tool. If fuse blows, go to step  23 . If fuse does not blow, check for intermittent problem. See INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 5.7L CORVETTE article.
  15. Turn ignition OFF. Remove fuel pump relay. Turn ignition ON, with the engine OFF. Probe the ignition 1 voltage circuit of the fuel pump relay, switch side, with a test light that is connected to a good ground. If test light illuminates, go to next step. If test light does not illuminate, go to step  26 .
  16. Connect fused jumper wire between fuel pump relay battery feed circuit and fuel pump power feed circuit at relay cavities. If fuel pump runs, go to step  21 . If fuel pump does not run, go to next step.
  17. Remove the left rear wheelhouse panel. Disconnect the fuel pump harness in-line connector. Test the supply voltage circuit of the fuel pump between the fuel pump relay and the fuel pump harness in-line connector for an open and for high resistance. See Figure . Repair as necessary. After repairs, go to step  30 . If circuit is okay, go to next step.
    18. NOTE: Inspect the ground circuit for proper torque, corrosion on the terminals, and damage to the wiring harness.
  18. Test the ground circuit of the fuel pump for an open and for high resistance between the fuel pump harness in-line connector and ground. Repair as necessary. After repairs, go to step  30 . If circuit is okay, go to next step.
  19. Test for an intermittent and for a poor connection at the fuel pump harness in-line connector. Repair as necessary. After repairs, go to step  30 . If circuit is okay, go to next step.
  20. Remove the left fuel tank. See FUEL TANKS (WITH FEEDBACK FUEL SYSTEM) under FUEL SYSTEMS in REMOVAL & INSTALLATION - CORVETTE article. Inspect the fuel sender harness on top of the fuel tank for damage to the harness or an open circuit. Repair as necessary. After repairs, go to step  30 . If circuit is okay, go to step  23 .
  21. Test for an intermittent and for a poor connection at the fuel pump relay. Repair as necessary. After repairs, go to step  30 . If connections are okay, go to step  28 .
  22. Test for an intermittent and for a poor connection at the PCM. Repair as necessary. After repairs, go to step  30 . If connections are okay, go to step  29 .
  23. Test for an intermittent and for a poor connection at the fuel pump connector within the fuel tank. Repair as necessary. After repairs, go to step  30 . If connections are okay, go to step  27 .
  24. Repair the short to voltage in the supply voltage circuit of the fuel pump. After repairs, go to step  30 .
  25. Repair the open or high resistance in the ground circuit of the fuel pump relay. After repairs, go to step  30 .
  26. Repair the open in the ignition 1 voltage circuit of the fuel pump relay. After repairs, go to step  30 .
  27. Replace the fuel pump. See FUEL SENDER ASSEMBLY (WITH FEEDBACK FUEL SYSTEM under FUEL SYSTEMS in REMOVAL & INSTALLATION - CORVETTE article. Replace the F/PMP fuse if necessary. After repairs, go to step  30 .
  28. Replace the fuel pump relay. After repairs, go to step  30 .
  29. Replace the PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - CORVETTE article. After repairs, go to next step.
  30. Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to step  2 .
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