Replacement of the CNG High-Pressure Fuel Filter Element

sd mm 47.07.001

CNG filter element replacement cycles are an important factor in maintaining the CNG fuel system integrity and ensuring maximum operating performance. Actual frequency of the filter element replacement could increase or decrease depending on the cleanliness of the fill station fueling system.

  1. Shut down the engine and apply the parking brake.
  2. Close the CNG fuel cylinder shutoff valves.
  3. Start the engine and let it idle until the fuel lines are empty and the engine stops. The gauges on the fuel panel should now read at or near 0 psi.
  4. Close the manual fuel shutoff valve on the fuel panel.
  5. Remove the two capscrews that secure the access cover to the fill panel, then remove the access cover. See Fig.. Save the capscrews for reinstallation.

    1. Fuel Panel Access Cover

    2. Capscrews (qty 2)

    3. Wiring Harness

    4. Pressure Relief Valve and Cap

    5. Coolant Outlet Line

    6. Coolant Inlet Line

    7. Fuel Inlet Line (to fuel cylinders)

    8. Fuel Outlet Line (to engine)

    Fig. 1, CNG Fuel Panel Assembly

  6. Slowly open the bleed valve on the manifold to relieve remaining fuel pressure within the system. See Fig..

    1. Coolant Inlet Port

    2. Coolant Outlet Port

    3. Pressure Relief Valve

    4. Pressure Regulator

    5. Wiring Harness

    6. Manifold Bleed Valve

    7. Manifold

    8. Manual Fuel Shutoff Valve

    9. Fuel Fill Port

    10. Filter Housing

    11. Filter Bowl

    12. Filter Drain Plug

    13. Solenoid Valve

    14. Fuel Line To Cylinders

    Fig. 2, CNG Fuel Panel Components

    7. Important: Some pressure may remain in the fuel system between the solenoid valve and the engine. Use caution when loosening fittings, as a small amount of gas may leak out.

  7. Put a clean receptacle under the filter assembly. Using a 1-1/4-inch wrench, unscrew the filter bowl from the filter housing.
  8. Remove and discard the filter element.
  9. Install a new filter element in the filter housing.
  10. Inspect the O-ring on the filter housing for damage or cracks. If necessary, replace the O-ring.
  11. Install the filter bowl on the filter housing. Tighten 90 lbf·ft (122 N·m).
  12. Close the bleed valve on the manifold and open the manual fuel shutoff valve on the fuel panel.
  13. Open the fuel cylinder shutoff valves.
  14. Using a methane detector, leak test all fuel system components between the fuel cylinders and the solenoid valve. A bubble solution can be used to pinpoint the exact location of leaks.
    Repair or replace any leaking components.
  15. Using the two capscrews removed previously, install the access cover on the fill panel.
Note:
Parent topic: Fuel
Document Number: 0000120393
Manual Publication Date: 2024-05-23
Topic Publication Date: 2024-11-06