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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 119 (Engine Control System - Basic Diagnostic Procedures) >> No-Start Diagnosis >> No Start - Engine Cranks Okay (3.8L) >> Fuel Pump Electrical Circuit (Except VIN K - Grand Prix)

Fuel Pump Electrical Circuit (Except VIN K - Grand Prix)

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  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 in appropriate SELF-DIAGNOSTICS article.
  2. Install a scan tool. Turn ignition on, with engine off. With scan tool, command fuel pump relay on and off. Does fuel pump turn on and off? If yes, problem is intermittent. If yes, go to next step.
  3. With a scan tool, command the fuel pump relay on and off. Do you hear a click when you command the fuel pump relay on and off? If yes, go to step  9. If no, go to next step.
  4. Turn ignition off. Disconnect fuel pump relay. Turn ignition on, with engine off. Probe the control circuit of the fuel pump relay with a test light connected to a good ground. With scan tool, command fuel pump relay on and off. Does the test light turn on and off? If yes, go to next step. If no, go to step  6.
  5. Connect a test light between the control circuit of fuel pump relay and ground circuit of the fuel pump relay. With scan tool, command fuel pump relay on and off. Does test light turn on and off? If yes, go to step  19. If no, go to step  22.
  6. Does test light remain illuminated with each command? If yes, go to next step. If no, go to step  8.
  7. Test fuel pump relay control circuit for a short to voltage. Did you find and correct the condition? If yes, go to step  27. If no, go to step  26.
  8. Test the control circuit of the fuel pump relay for a short to ground or an open. Did you find and correct the condition? If yes, go to step  27. If no, go to step  20.
  9. Turn ignition on, with engine off. Does the fuel pump operate continuously? If yes, go to next step. If no, go to step  11.
  10. Turn ignition off. Disconnect fuel pump relay. Turn ignition on, with engine off. Does fuel pump operate continuously? If yes, go to step  21. If no, go to step  25.
  11. Is fuel pump fuse open? If yes, go to next step. If no, go to step  14.
  12. Test fuel pump supply voltage circuit for a grounded circuit between fuel pump fuse and fuel pump. Replace fuel pump fuse if necessary. Did you find and correct the condition? If yes, go to step  27. If no, go to next step.
  13. Install all disconnected electrical components. Install a new fuel pump fuse. With scan tool, turn fuel pump on. Is fuel pump fuse open? If yes, go to step  24. If no, problem is intermittent.
  14. Turn ignition off. Disconnect fuel pump relay. Turn ignition on, with engine off. Probe the battery voltage circuit of fuel pump relay switch with a test light connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step  23.
  15. Connect a 20-amp fused jumper wire between the battery voltage circuit of fuel pump relay switch and supply voltage circuit of the fuel pump. Does the fuel pump operate? If yes, go to step  19. If no, go to next step.
  16. Test the supply voltage circuit of the fuel pump for an open or high resistance between the fuel pump relay and the fuel pump. Did you find and correct the condition? If yes, go to step  27. If no, go to next step.
  17. Test the ground circuit of the fuel pump for an open or high resistance. Did you find and correct the condition? If yes, go to step  27. If no, go to next step.
  18. Inspect for poor connections at fuel pump. Did you find and correct the condition? If yes, go to step  27. If no, go to step  24.
  19. Inspect for poor connections at fuel pump relay. Did you find and correct the condition? If yes, go to step  27. If no, go to step  25.
  20. Inspect for poor connections at PCM harness connector. Did you find and correct the condition? If yes, go to step 27. If no, go to step  26.
  21. Repair fuel pump supply voltage circuit for short to voltage. After repairs, go to step  27.
  22. Repair open fuel pump relay ground circuit. After repairs, go to step  27.
  23. Repair battery voltage circuit of fuel pump relay switch. After repairs, go to step  27.
  24. Replace fuel pump. Replace fuel pump fuse, if necessary. After replacing fuel pump, go to step  27.
  25. Replace fuel pump relay. After replacing relay, go to step  27.
  26. Replace PCM. After replacing PCM, go to next step.
  27. 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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