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Can't Fill Up, tank won't take fuel.

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  • Can't Fill Up, tank won't take fuel.

    So, I just bought a 98 F150 bi fuel. It switches and runs just fine, but only when I'm connected to the Fill Station. The tank reads empty, I hook up, fill the lines with gas and the tank reads full. The truck will run for about a minute and then die on an empty tank.

    All of the cables are connected to the tank, and the fuses on the GFI are good. I did notice that only one of the relays on the GFI is hooked up, but I can't find another cable so I don't think that's the problem.

    What should I be looking for?
    Where does the power come from to operate the tanks valve, and is there a manual shut off that might have been shut by the previous owner?

    Hope someone out there has experience to share,



  • #2
    F-150 Tank fueling woes.

    So I tested the electronic valve, it pings when I turn on the car and when I manually apply 12 volts, so I know it's opening. Is it possible to manually close down a bolt on the valve to keep it closed in spite of what the electronic valve is doing?

    There are two threaded holes, one on the bottom of the tanks valve head, and 2 on the side. The bottom one has a red plastic cap covering it. Would one of those be the culprit?

    Here's a picture of the side.
    Last edited by mrbojangles; 05-28-2009, 07:07 PM.


    • #3
      Re: Can't Fill Up, tank won't take fuel.

      This is the side of the valve
      Attached Files
      Last edited by mrbojangles; 05-28-2009, 07:15 PM.


      • #4
        Re: Can't Fill Up, tank won't take fuel.

        First of all BE CAREFUL.

        The allen screw in the center of the big nut is the manual lock down screw and it looks like it is screwed in meaning it is off. You can try and slowly back out the allen screw (3/16"). Put a wrench on the nut when trying to back out the manual lock down screw just to be sure the nut does not move.

        With the key off, if gas starts to flow as you slowly back out the manual lock down, stop and trun it IN to shut the tank off again. Gas flowing means that the solenoid valve is defective. Stop at that point and take it to a trained technician.

        Without seeing the "red cap", it could be the dust cover for the PRD valve which is located in the valve assembly.

        Hope this helps and be careful



        • #5
          Re: Can't Fill Up, tank won't take fuel.

          LarryCNG you are a gene! Thank you. After opening the allen screw the truck started right up and ran. The tank was near empty though so It didn't last long.

          Something strange though, I could hear a loud hissing coming from under the hood, in the area of the GFI valve, but I didn't smell any gas. I'll search the forum for info, but in case someone stumbles on this post: any ideas as to what's going on?



          • #6
            Re: Can't Fill Up, tank won't take fuel.

            Great, you got it running.

            If there is a hissing under the hood, you have a LEAK. Use some leak detection fluid and spray around the components and look for bubbles. Don't use Windex or anything with ammonia

            You make some leak dector fluid with 1 part ultra Ivory and 5 parts water in a spray bottle. It is cheap, easy to do, and keeps your hands soft.



            • #7
              I can't figure out how to post another thread, but I am having the same problem. I can't fill my tank. If have a gfi valve, and am unsure exactly how to wire it. I have the white wire to 12v, the black wire to ground, and the purple and blue wire not hooked to anything. The valve clicks when 12v goes to it, but won't fill. What are the other two wire for and how do I hook them up?? Any help would be most appreciated!!
              Attached Files


              • #8
                You need to understand the valve before you go any further. You do not need any power to the valve to fill the tank. You only need power to allow fuel to exit the tank. Any one of the ports on the valve can be used for supply or fill with the exception of the port that the burst disc is installed in. Your'e not connected to that one---right? At least you haven't fried the temperature thermocouple--the wires that aren't white or black. Don't hook them to anything unless you want to monitor the fuel temperature. What is this tank installed in? Be really sure that the tank is not filled already as sometimes either the solenoid isn't functioning or the manual lockoff valve has been closed.


                • #9

                  siai47 is absolutely correct - Usually you cannot fill a tank because of a mechanical issue like the tank is in lock-down or a manual shut off valve has been closed (depends on you configuration). The GFI electronic valve will not normally let gas out when not energized but gas can go in. If someone put the tank in lock down I'd be curious as to why before I start messing with it.


                  • #10
                    Was the tank was locked down due to the under hood leak?
                    I have a question about locking down the tank with the 3/16 allen screw. For some reason i thought this was a permanent procedure that once done cannot be reversed or am i confusing this with another procedure??
                    Also is it common to lock down the valves with that allen screw prior to doing any work on the gas system?? Thanks


                    • #11
                      Locking down the valve with the Allen screw will not hurt the tank. There is a tool for venting the tank (forcing the valve open), that when used, will destroy the valve. Two different things. You should lock down the valve prior to working on the high pressure side of the system, however taking the power connector going to the valve apart will also prevent it from opening. The only possible problem is if the valve was stuck open or had failed open and you loosen a line things could get interesting. So just lock it down and be happy