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Newbie? Questions on New Cavalier

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  • Newbie? Questions on New Cavalier

    Just purchased a 2002 Cavalier. Runs great. Has about 1/4 tank of CNG and 3/4 tank of Gas. Car comes from Connecticut. I have no idea how long the gasoline has been in the car or how long since it has been driven on gasoline. My thought is to run the CNG out, run the gas down to almost empty and then fill both back up. Any other suggestions like adding an additive to the gas before it switches, how to avoid being stranded in case it doesn't switch, etc.?


  • #2
    Re: Newbie? Questions on New Cavalier

    You should run a full tank of gas through the car every 60 days. I usually drive a Cavalier until the CNG runs out and then drive on gasoline to the next station. By doing that I eventually use up a tank of gasoline.

    If you're nervous that the gasoline is old and want to test it at home before running out of CNG on the street you can force the car to run on gasoline with two different methods.

    You can get under the car and turn the 1/4 turn valve to turn off the CNG, thus forcing the engine to use gasoline.

    Or, while the car is turned OFF and the key is out, you can pull the CNG fuse from the fuse box underneath the hood on the driver's side towards the front of the car. This basically disables the whole CNG system and makes the car run on gasoline.

    Enjoy your new car.


    • #3
      Re: Newbie? Questions on New Cavalier

      graydon, CNG Utah,

      On the Cavalier there is no 1/4 turn valve to turn off the CNG under the car (that is only on Fords). There is an allen wrench screw that you can tighten on the solenoid valve on the tank, thus "locking the tank out". I prefer to "force" it to run on gasoline by turning the allen wrench and locking the tank out versus pulling the fuse. I've heard that if you pull the fuse, you set off codes in the OBDII system and then have to allow the car to run through a cycle to reset the codes.

      Whatever you do, make sure that the car is OFF before you do anything.
      Mountain Green, Utah
      2003 CNG Cavalier
      2003 CNG Silverado 2500HD


      • #4
        Re: Newbie? Questions on New Cavalier

        I would not turn allen screw in tank this could screw up the valve on the tank if it was me i would start car at home open hood unplugged low pressure lock out located beside low pressure regulater it will switch to gasoline you will get a service engine light after 3 starts it will go out


        • #5
          Re: Newbie? Questions on New Cavalier

          Pulling the CNG fuse will not set codes. Turn off the ignition, pull the fuse, throw it in the console and go on your way on gasoline. Disconnecting the feed to the HPL in the trunk will set a code which will reset as BruceEB stated. Only the 1998 model had a quarter turn shut off valve. I usually pull the fuse to switch to gasoline unless I need to depressurize the fuel lines, then the connector in the trunk is the way to go. You should avoid messing with the manual valve unless there is no other way to shut off the CNG flow.