Fuel System Cleaning (1)

Fuel System Cleaning

Warning

Refer to Diesel/Gasoline Vapors Warning.

Warning

Refer to Safety Glasses Warning. Diesel Exhaust Fluid (DEF) is a corrosive fluid that also tends to form deposits on components. In case of DEF contamination in the fuel tank, follow the guidelines below. If the in-tank fuel pump has been run, then it must be assumed that DEF has been pumped through both the low-pressure system and high-pressure pump. For this case, there are two scenarios:

1. Engine has not been cranked. In this case, the system from fuel fill pipe to the high-pressure fuel pump and the high-pressure pipe from pump to rail must be replaced along with the low-pressure return lines.
2. Engine has been cranked. In this case, the entire fuel system from fuel fill pipe to high-pressure fuel pump, fuel rail, injectors, injector return fuel lines, high-pressure fuel pipes and low pressure return lines must be replaced. If the in-tank fuel pump has not been run, the fuel fill pipe, tank and fuel pump module should be replaced. The following procedure should not be used for cases of DEF contamination. Fungi and other microorganisms can survive and multiply in diesel fuel if water is present. The fungi can be present in any part of the fuel handling system. These fungi grow into long strings and will form into large globules. The growths appear slimy and are usually black, green, or brown. The fungi may grow anywhere in the fuel but are most plentiful where diesel fuel and water meet. As the fuel is agitated, when service station tanks are being filled, fungi are distributed throughout the tank and may be pumped into a vehicle. Fungi use the fuel as their main energy supply and need only trace amounts of water and minerals. As they grow and multiply, they change fuel into water, sludge, acids, and products of metabolism. The most common symptom is fuel filter plugging; however, various metal components including the fuel sending unit, pipes, fuel injectors, and injection pump can corrode. If bacterial growth is found in the fuel system, the proper method of removal is to flush the fuel system using the appropriate Service Information procedures, replace the fuel filter element and refill the tank with clean diesel fuel. Fuel system flushing should be conducted using a GM recommended or regional equivalent diesel fuel system cleaner. The presence of water or gasoline in diesel fuel may also cause injection pump and nozzle damage. This procedure checks for the presence of water, gasoline and fungi/bacteria in diesel fuel that may cause injection pump and nozzle damage. Remove and inspect the fuel filter element. If water, gasoline or fungi/bacteria are not present, end the inspection. If water or fungi/bacteria are present, proceed to Cleaning Water from the Fuel System. If gasoline is present, proceed to Cleaning Gasoline from the Fuel System. Cleaning Water from the Fuel System
3. Disconnect the negative battery cable(s). Battery Negative Cable Disconnection and Connection
4. Remove the fuel sender assembly. Fuel Tank Fuel Pump Module Replacement
5. Inspect the fuel tank and the fuel sender for rust, fungi or bacteria. If there is rust, replace the rusted components.
6. Clean the inside of the fuel tank and the fuel sender with hot water.
7. Use compressed air in order to dry the fuel tank and the fuel sender.
8. Disconnect the ends of the following lines: The fuel filter inlet line (both ends) The transfer pump pressure line and suction line (if applicable) The fuel filter outlet line (both ends) The fuel filter drain The fuel return line (both ends)
9. Inspect each of the pipes and lines.
10. Replace any rusted or contaminated pipes.
11. Clean the inside of the fuel filter housing.
12. Dry the fuel filter housing with compressed air.
13. Dry the inside of each line with low pressure air.
14. Disconnect the crankshaft position sensor. Crankshaft Position Sensor Replacement
15. Install a new fuel filter. Fuel Filter Replacement
16. Install the fuel sender assembly. Fuel Tank Fuel Pump Module Replacement
17. Add clean diesel fuel to the primary tank until the tank is ¼ full.
18. Reconnect the following lines: The fuel filter inlet line The fuel filter outlet line The transfer pump pressure and suction (both ends) lines The fuel return line (tank end)
19. Connect the fuel filter drain to a line that flows into a clean metal container.
20. Connect the negative battery cable(s). Battery Negative Cable Disconnection and Connection
21. Using the scan tool control function, cycle the fuel pump relay to operate the fuel pump until clean fuel flows from the fuel filter drain into a metal container.
22. Close the fuel filter drain and remove the bleeder hose.
23. Install a hose on the fuel return line and insert other end into a 7.6 liters (2 gallon) metal container.
24. Prime the fuel system until 3.8 liters (1 gallon) of fuel has passed into the container. Fuel System Priming
25. Reconnect the fuel return line.
26. Reconnect the crankshaft position sensor. Crankshaft Position Sensor Replacement
27. Start and run the engine. If the engine does not start, prime the fuel system. Fuel System Priming
28. Stop the engine.
29. Clean any fuel spillage from the engine.

Warning

Avoid physical contact with the biocides in order to avoid personal injury.

28. Fill the fuel tank and add a biocide, if needed.
29. Clear the engine control module of any diagnostic trouble codes (DTC’s). Cleaning Gasoline from the Fuel System
30. Drain the fuel tank.
31. Disconnect the crankshaft position sensor. Crankshaft Position Sensor Replacement
32. Fill the fuel tank to ¼ full.
33. Loosen the fuel filter drain and connect the filter to a hose that flows into a metal container.
34. Using the scan tool control function, cycle the fuel pump relay to operate the fuel pump until clean fuel flows from the fuel filter drain into a metal container.
35. Hand tighten the fuel filter drain and disconnect the hose.
36. Install a hose on the fuel return line and insert the other end into a 7.6 liters (2 gallon) metal container.
37. Prime the fuel system until 3.8 liters (1 gallon) of fuel has passed into the container. Fuel System Priming
38. Reconnect the fuel return line.
39. Reconnect the crankshaft position sensor. Crankshaft Position Sensor Replacement
40. Start and run the engine for 15 minutes. If the engine does not start, prime the fuel system. Fuel System Priming
41. Stop the engine.
42. Clean any fuel spillage from the engine.
43. Clear the engine of any diagnostic trouble codes (DTCs).