No announcement yet.

2004 Cavalier Will not switch to gasoline when CNG tank empties.

  • Filter
  • Time
  • Show
Clear All
new posts

  • 2004 Cavalier Will not switch to gasoline when CNG tank empties.

    The fuel pump went bad on my 2004 Cavalier. So we towed the car to a CNG station and filled it. We then brought the car home and replaced the fuel pump. After replacing the fuel pump I pulled the alternative fuel relay to make it start on gasoline. The car would not start on gasoline with relay out. I did some troubleshooting looking for problems and found nothing. The next day I was back looking and all of the sudden all voltages were what they should be and the car started and ran fine on gasoline with alt. fuel relay out. She drove the car for a while and CNG tank emptied and car switched to gasoline just like it is supposed to. After refilling CNG tank, the car switched back to CNG, just like ti is supposed to. Then she ran that CNG tank dry and the car did not switch to gasoline and she stranded again. So I Hooked a wire directly to the fuel pump and the fuel pump came on, but the car would not start. We disconnected the jumper wire and put everything back together and prepared to tow it again to the CNG station. Just before we left, we tried to start it one last time before towing and it started on gasoline. We drove it to CNG and decided that at least for now, it is a dedicated CNG car. I would however like to get this fixed. She is a young teenage girl and drives about 100 miles a day and has to fill almost everyday at a dimly lit CNG station.

  • #2
    I would change relay and check for bad connection.


    • #3
      After troubleshooting, I determined there was a loose wire somewhere, I had no access to wiring diagrams so I brought it to Rons Shell in St George, Utah. He is the local CNG repair guy. After a couple days of trying to make it fail, it finally did and he determined it was a bad ignition switch. All fixed now and running on either fuel, just like it is supposed to. Car will be going up for sale soon. It is in Hurricane, Utah,