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CNG Leaking big time at fill up

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  • CNG Leaking big time at fill up

    2000 F-150 Bi-Fuel. When i try to fill CNG is leaking all the time, to the point where it will start to ice. Only did that once. Latest try, when i started to pressurize the system after connecting the hose I had a big blast of gas so I decided to pass on the fill up. I am guessing that it is probably just the o-rings that are damaged or missing. Is this a case i need to take to Ford to fix or are parts common that another CNG shop should be able to fix. Truck is running fine on gas right now, but really hate to burn that stuff.

    Ralph

  • #2
    Re: CNG Leaking big time at fill up

    Go see Curtis Martin at Robertson Honda. He also operates the cng station at the dealer. The o- ring should be the same as on A honda GX, ( parker makes the fitting on both). The fitting is available as an aftermarket item for a hundred or so. It's about $600 at ford !!!!! ( No Typo)!!!!!!

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    • #3
      Re: CNG Leaking big time at fill up

      It is a stock O ring available at any hardware store I am sorry I don't remember the size. Hopefully some one can chime in with it.

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      • #4
        Re: CNG Leaking big time at fill up

        I had the same thing happen on my 02 civic and went to autozone and got one of those AC o-rings that they have for couple bucks. I always carry a spare in case I forget to check to see if the o-ring is sticking to the tip of the pump hose. If CNG leaks it will leave a frost on any metal surface it's leaking on. Pretty late post but hope it helps anyone with the same problem in the future.

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        • #5
          Re: CNG Leaking big time at fill up

          I have a similar problem with a 2003 Ford E350 van. It leaks gas constantly after I remove the filler hose. It appears that I need a new receptacle. (male fitting) Does anybody have a source for these? I also need to know the correct procedure for replacing this, and this involves venting the lines. Any manuals out there?
          Thank you for allowing me to add this to your post.

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          • #6
            Re: CNG Leaking big time at fill up

            The Oring in the receptacle is a special hardness. You can use an Oring from the hardware store but you will be replacing it more often as it is softer and will tend to blowout. I have the proper Orings listed at or in the CNG category.

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            • #7
              Re: CNG Leaking big time at fill up

              ngasvan... Try spraying a dry silicone into the receptacle and spray some into the nozzle just before coupling to the receptacle and fueling so the pressure forces it through the check valve. Do not use any other petroleum based sprays as they will swell the oring. It may work but the check valve may be too far gone and need a replacement receptacle.

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              • #8
                Re: CNG Leaking big time at fill up

                I called the Ford dealer to get a price on the new filling receptacle, they quoted around $1000.00. I thought that was pretty funny.
                I then called a PARKER Hydraulics dealer and purchased a #FMS-362-6FO Fitting for around $70.00. Fit perfect, no more leak.
                This receptacle has a 9/16-18 thread and a spot for the o-ring to seat, just like the original from Staubli (Ford). Amazing how Ford will go out of their way to NOT support these vehicles.

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                • #9
                  Re: CNG Leaking big time at fill up

                  ngasvan, What procedure did you follow when changing the fitting? Did you manually close the tank valves or just disconnect the wires and let the engine run out of fuel? JOE

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                  • #10
                    Re: CNG Leaking big time at fill up

                    I used an allen wrench and gently closed (clockwise) each tank valve, started the engine and let it stall. I then loosened the fill receptacle from the line, let it leak empty, then carefully unscrewed it the rest of the way. No issues at all. There is an O-ring on the 9/16-18 nipple that the fill receptacle screws onto, be sure it is in good shape and lightly lubricate with silicone O-ring lube. Tighten the new fitting on snugly.
                    You might find it easier to remove the filler assembly from the vehicle at the line fitting that is about 12 inches below the receptacle, then work on the new fitting with the whole thing in a vise. This is how I did it.

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                    • #11
                      Re: CNG Leaking big time at fill up

                      I forgot to mention that you MUST close the tank valves first! The tanks are piped directly to the fill fitting! There is 3600 psi of gas pressure behind it! Then you HAVE to bleed the system empty before removing it.

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                      • #12
                        Re: CNG Leaking big time at fill up

                        Whatever became of your truck? Did you ever experience a pop noise from the front passenger area near the ground?

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