2001 GMC C3500 HD 6.5 F, AutomaticFACTORY OEM SERVICE PROCEDURE

Installation Procedure

  1. Install the water- in- fuel sensing element using a new seal. Refer to Water-in-Fuel Sensor Replacement .
  2. Install the heater element with a new O-ring seal. Refer to Fuel Heater Element Replacement .
  3. Install the fuel filter into the fuel manager. Refer to Fuel Filter Replacement .
  4. Install the fuel manager/filter. Refer to Fuel Filter/Heater Element Housing Replacement .
  5. Install the fuel sender. Refer to Fuel Sender Assembly Replacement .
  6. Install the fuel tank. Refer to Fuel Tank Replacement (Extended Cab Side Tank)  or Fuel Tank Replacement (Cab and Chassis Rear Tank)  or Fuel Tank Replacement (Cab and Chassis Side Tank) .
  7. Install the new fuel lift pump. Refer to Fuel Pump Replacement .
  8. Install clean diesel fuel into the tank until 1/4 full.
  9. Install the fuel tank cap.
  10. Install the negative battery cables.
  11. Remove the ECM 1 fuse from the underhood relay center.
    12. IMPORTANT: Use a suitable container to catch the fuel.
  12. Install a hose from the fuel injection pump inlet hose (hose to hose) at the fuel injection pump to a closed metal container with a capacity of at least 8 liters (2 gallons).
  13. Crank the engine for 15 seconds with one minute cooling periods until the clean fuel is pumped out.
  14. Reinstall the inlet hose to the injection pump.
  15. Install the ECM 1 fuse in the underhood relay center.
  16. Install a hose from the return line at the fuel injection pump to a closed metal container with a capacity of at least 8 liters (2 gallons).
  17. Crank the engine for 15 seconds with one minute cooling periods until clean fuel appears at the return line.
      IMPORTANT: Ensure the fuel return line is in the metal container and that the container does not overflow.
    • Start the engine and allow to idle for 5 minutes.
    • Remove the hose from the metal container.
  18. Reinstall the fuel return line to the injection pump.
  19. Check for leaks.
  20. Clear any engine DTCs.
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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