Hey gang, CNGchat needs your help!

For over a decade we have enjoyed providing this little corner of the Internet for folks to discuss all things natural gas vehicles. It is the largest forum of its kind: with some 70,000 posts on over 11,000 topics. But with continued low gasoline & diesel prices and strong automaker support for electric vehicles, consumer interest in CNG has dropped considerably, and with it has visitor traffic here. As a result, Google ad revenues no longer cover hosting fees.

If you find CNGchat to be a useful resource then please consider making a modest donation to support keeping this remarkable pool of knowledge available to the alternative fuels community. Thanks!

See more
See less

PLEASE HELP: Car Won't Start. Fuel Gauge Says Empty.

  • Filter
  • Time
  • Show
Clear All
new posts

  • PLEASE HELP: Car Won't Start. Fuel Gauge Says Empty.

    Long story short, bought a 2007 Civic GX a month ago. Drove around in. Tried to change the spark plugs, but they were seized and broke. So I had a mechanic replace the whole motor and trans.

    I dropped off the car with half a tank at the mechanic. Now he's done and the car says EMPTY. Flashing fuel light. Weird but ok, I towed it to the station to fill up. I got about 3 gallons in and then the pump stopped.
    Car still stays it's empty and it will not start.

    Any ideas?? Me and the mechanic are out of ideas. Both new to CNG cars. Please help with any ideas you think it could be.

  • #2
    Your tank is full. 6gge usually is a full fill even though it is a 8gge tank. So, you don't have a fuel problem.

    Check this thread elsewhere in the forum. Everything you ever wanted to know about the pressure regulator leading to the fuel rail:


    • #3
      Thanks, I'll take a look!


      • #4
        I'm not familiar with the Honda setup but I suspect many CNG cars have a similar setup. If the tank solenoids are not opening, you can still fill it but there will be no pressure between the tanks and the input side of the regulator (which is probably where the fuel sender is). I would check to see if something is disconnected from the circuit that opens the high pressure solenoids on the tanks. Also, I'm not sure on the Honda if the fuel sender is before or after the main shutoff valve. If it is after the shut off valve--that may be just that simple.


        • #5
          Get a helper. 1, Disconnect the positive term of the battery for 15 minutes . 2,Turn the key to ON , do not try to start at this point. 3 , Open the trunk, 4 While your helper puts the battery terminal back on, listen for a click or clunk from the trunk. Helps to remove the liner to expose the tank solenoid. Needs to be quiet to hear the tank solenoid . Report back here with findings.If you have any leaks in the cng lines, or a leeky fuel injector, the computer will interpet this as a leak and inhibit the tank solonoid.
          Last edited by Lakewood90712; 10-22-2018, 09:26 PM.


          • #6
            Yes, look for the 1/4 turn manual shutoff valve near the driver rear tire.. that would be an easy fix if this is the case... perpendicular = closed. But my hunch is the tank solenoid isn't opening. You should hear an audible "click" on the neck of the tank when the key is turned on. Do you have any fuel rail pressure?


            • #7
              Yes ,I totally forgot about the red handle shutoff valve. Thanks John.


              • #8
                I pulled the battery and let it sit over night. Threw it back in and the fuel gauge read full. Tried to fire it up and nothing. No click from the rear either.

                Fuel gauge went back to empty and blinking.

                Opened the fuel rail and vented the pressure (yes there was some). Reconnected. Tried to start again, nothing. No click from the rear, no start.


                • #9
                  From little research I've done. It seems like the tank solenoid isn't opening. But these rarely go bad.
                  And every scenario keeps it from opening (cold starts, bad thermo valves, too much oil in the fuel filter, too much pressure in low side lines, etc).

                  I just can't figure it out. Both engines were (essentially) running before the swap.


                  • #10
                    I think your problem is stuck closed tank valve , won't let fuel out of the tank. This is a common problem with 2006 to 2013 Civics .
                    If that's the case . I think Honda has a Manufacture warranty 10 years or 150,000 miles. But call Honda dealer to confirm.
                    If you have any further questions in regards to your concern, feel free to call me at my shop # 949-305-3333 . Mike's Advanced Auto Care , Mission Viejo, Ca.