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Diagnostic Procedure (Without 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 Fig 1 . 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  19 . If test light does not turn on and off, go to step  23 .
  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  28 . If circuit is okay, go to step  27 .
  8. Check for open or short to ground in fuel pump relay control circuit. Repair as necessary. After repairs, go to step  28 . If circuit is okay, go to step  20 .
  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  22 . If fuel pump does not run continuously, go to step  26 .
  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  14 .
  12. Check for short to ground in fuel pump power feed circuit between fuel pump and fuse. See Fig 4 . Repair as necessary. After repairs, go to step  28 . If circuit is okay, go to next step.
  13. Reconnect all components. Install NEW F/PMP fuse. Using scan tool, command fuel pump relay ON. If fuse blows, go to step  25 . If fuse does not blow, check for intermittent problem. See INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 5.7L CORVETTE article.
  14. Turn ignition off. Disconnect fuel pump relay located in underhood fuse block. Turn ignition ON. Using test light connected to ground, probe fuel pump relay battery feed circuit at relay cavity. If test light illuminates, go to next step. If test light does not illuminate, go to step  24 .
  15. 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  19 . If fuel pump does not run, go to next step.
  16. Check for open or high resistance in fuel pump power feed circuit between fuel pump relay and fuel pump. Repair as necessary. After repairs, go to step  28 . If circuit is okay, go to next step.
  17. Check for open or high resistance in fuel pump ground circuit. Repair as necessary. After repairs, go to step  28 . If circuit is okay, go to next step.
  18. Check for poor connections at fuel pump. Repair as necessary. After repairs, go to step  28 . If connections are okay, go to step  21 .
  19. Check for poor connections at fuel pump relay. Repair as necessary. After repairs, go to step  28 . If connections are okay, go to step  26 .
  20. Check for poor PCM harness connections. Repair as necessary. After repairs, go to step  28 . If connections are okay, go to step  27 .
  21. Test for an intermittent and for a poor connection at the fuel pump connector within the fuel tank. After repairs, go to step  28 . If connections are okay, go to step  25 .
  22. Repair short to voltage in fuel pump power feed circuit. After repairs, go to step  28 .
  23. Repair open in fuel pump relay ground circuit. After repairs, go to step  28 .
  24. Repair open in fuel pump relay battery feed circuit. After repairs, go to step  28 .
  25. Replace fuel pump. After repairs, go to step  28 .
  26. Replace fuel pump relay. After repairs, go to step  28 .
  27. Replace PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - CORVETTE article. After repairs, go to next step.
  28. Operate system to verify repair. If system operation is okay, testing is complete. If system operation is not okay, go to step  2 .
Fig 1: Identifying Underhood Fuse Block Details
G00232259Courtesy of GENERAL MOTORS CORP.
Fig 2: Identifying Fuel Pump In-Line Connector Terminals (With Feedback Fuel System)
G00232269Courtesy of GENERAL MOTORS CORP.
Fig 3: Identifying Fuel Pump/Sender Assembly Connector Terminals (With Feedback Fuel System)
G00250948Courtesy of GENERAL MOTORS CORP.
Fig 4: Identifying Fuel Pump/Sender Assembly Connector Terminals (Without Feedback Fuel System)
G00250949Courtesy of GENERAL MOTORS CORP.
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