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Need advice on 2000 Cavalier

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  • Need advice on 2000 Cavalier

    OK. I've got a 2000 CNG Cavalier here in Bennington, Vermont, which has failed state inspection because of rust on the frame near the rear wheel wells. The car only has 127,000 and runs beautifully on gasoline. It stopped running on CNG about three years ago. My theory as to why it won't run on CNG, based on what I've read in this forum, is that it got a fill at Newark Airport that was well in excess of 3,600psi. The orange light stays on continuously. I haven't concerned myself with fixing the CNG problem because there are no CNG stations in Southern Vermont, the price of gasoline is cheap, and my tank expired in 2014.

    My problem now is that the local welder who was going to patch my frame won't do it because the CNG lines run right where the rust is.

    So do I try and find somebody to de-commission the CNG system or do I just scrap the car and maybe try and sell the AF-ECU?

    Any ideas would be appreciated.

  • #2
    You have to find someone to get the CNG drained from the tank. This is required if you repair it or scrap it. If you think the tank is overfilled (which I doubt) and it is expired there are two additional reasons to get the tank taken care of. Once the tank is drained which takes a special tool and someone who knows what they are doing, then you can take care of the necessary frame repair. There is no cost benefit to re-tanking the car with an unexpired tank and then trying to figure out what is actually wrong with the car. The components such as the AF-ECU taken from a non-functional car are worth almost nothing. The car is almost 18 years old and if you owned it during the time of high gasoline prices than it has paid for itself. You could probably buy a regular 2000 Cavalier with a good frame for less than the repair cost if you are really attached to Cavaliers. BTW--the lines on the right side of the car in the frame area are coolant lines which can be plugged if cut. CNG is only present near the left rear frame area. However, the tank issue needs to be addressed regardless of what you do.

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    • #3
      Yes, by all means have the CNG tank emptied.

      Using the link above under "Find Certified CNG Tank Inspectors" the CSA database came up with this one covering New England. You might want to call him:
      http://www.c2altfuelsllc.com/

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      • #4
        Please sell me the ecu and harness piece. I'm in CT. Please

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        • #5
          IIRC the 2002 did not have a separate AFU ecu. it was the only year with the old style cng fuel system that incorporated all functions into the main ecu. If you are going to de commission the cng system, it should be able to be re flashed as a gasoline only. SIAI 47 will know for sure

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          • #6
            You should be able to remove the tank, lines, and the whole underhood assembly with the regualtor, lock off valve and GMS/MCV. You would need to get a standard Cavalier plastic duct that goes from the air cleaner to the throttle body to replace the CNG part. You could also cap the duct where the hose from the GMS/MCV connects to intake system, however you don't want any leaks in the duct so best get the original gasoline car part. I would try to run it without a reflash. You will most likely get a "check engine" light but that's about it. If it can't get into the ready mode for CNG operation, it will just default to gasoline operation.

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