Occasionally a driver has an issue with fueling CNG because they are missing the o-ring on the fuel tank receptacle where the dispenser fueling nozzle connects to the tank. The nozzle does not properly seal to the tank receptacle if the o-ring is missing. The black rubber o-ring is visible on the inside of the tank receptacle as shown in the picture below. If the o-ring is missing, then the dispenser nozzle and tank receptacle will not form a tight seal and CNG can leak during fueling. Fortunately the fix is easy. A replacement o-ring is just inserted inside the face of the receptacle. No special skill is needed. Spare o-rings can be ordered from your fuel system manufacturer and stored in the truck for a quick and easy solution. You need to know the manufacturer of your CNG fuel system (e.g., Agility, Momentum or Quantum), and the size of the receptacle that is missing the o-ring. The large receptacle is called a CT5000. The standard size receptacle is a CT1000. Both size replacement o-rings can be stored in the truck to cover both possibilities. The black rubber o-ring is visible on the inside of the tank receptacle as shown in the picture.
Agility Fuel Systems
CT1000 o-ring is part # 10500025
CT5000 o-ring is part # 10500047
Momentum Fuel Systems
Quantum Fuel Systems