Squeak/Rattle Noise from Eng Compartment or Cab Floor (Reposition CNG Fuel Line)

Some owners may comment on a squeak or rattle noise coming from the engine compartment or from the floor of the cab.

During installation or after major repairs, improper orientation of the CNG medium pressure fuel line may cause the line to contact the body flange (1) in the transmission tunnel area. This contact may result in a squeak or rattle condition.

Verify that the transmission harness and the High Pressure Regulator (HPR) coolant hoses are properly routed and do not interfere with the CNG medium pressure fuel line. If interference exists, reposition the CNG medium pressure fuel line using the following procedure and the part number listed below.

1. Remove the three-way clamp (1) from the CNG and the gasoline fuel lines. Discard the clamp.



2. Using a 3/4 inch open-end wrench at the underhood (UH) fuel line union, carefully reposition the fuel line by turning the wrench clockwise until the fuel line contacts the transmission case.
3. Verify that the line has been repositioned and that there is about 12.7 mm (1/2 in) clearance between the body flange and the line. The line should run parallel to the gasoline fuel lines.



4. Install one new retainer on the CNG and the gasoline fuel lines near the distributor in the UH area.



5. Install one new retainer on the CNG and the gasoline fuel lines behind the HO2S connector clip in the underbody area.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: