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    another fuel tank thread

    So a year ago I tried converting my tank to a 2-pump configuration with a second pump on the drivers side, but it didn't work well for several reasons. First, it was hard to keep the sender both sealed and insulated and it wanted to leak gas. Worse, it did work really well to the point that the driver's side would transfer all the fuel to the pax side and the pump would fail after running dry.

    So, I engineered my current solution which I have now tested for several events and I can say it works!

    The goal was not to have extra plumbing with a swirl pot or additional fuel pumps as points of failure. This project involved cutting the tank open, adding baffles and a trap door, and sealing it back up. Pressure tested, naturally. In my testing fuel is kept at the pump down to 1 gallon with 1G left and right turns. I've run it on track well below the fuel low light on several occasions now without issue.

    The only downsides I've encountered is that the fuel level will read slightly high during hard maneuvering as the fuel is concentrated in the pump section (but during straight and level driving there's a bleed passage that equalizes everything and it reads normal). Second, the tank takes a bit longer to fill. It won't fill at full pump volume without triggering the auto-shutoff. I think making the baffles about an inch lower would totally solve that, or I might have a venting issue. I don't completely understand it yet because the vertical baffle isn't any higher than the saddle, and that doesn't limit fueling flow..

    I'm on a fresh set of Falkens and the conditions are ideal. Shelby has 500+ HP and dusts me on the straights.




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    #2
    Neat! Nice work.

    What kind of gasket/sealant did you use for the trap door?

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      #3
      The trap door came with a gasket. For all of the gaps I used the same stuff we use to seal commercial aviation (and military...) fuel tanks. Flamemaster Chemseal 6 Oz Cs3204 B1/2 By Aircraft Spruce, a polysulfide two-part sealant.

      I threw-up a video of an early test on the first tank to show it working. You can see the equalization bleed through at the end. https://www.youtube.com/shorts/CuFdCJTrNgI in my first iteration the trap door wasn't canted, it doesn't work as well vertical but when it's canted gravity helps keep the door sealed (it has a rubber O-ring seal, super nice!)
      Last edited by hoveringuy; 05-29-2023, 08:32 AM.

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        #4
        Did you end up welding the tank back closed?
        Any tips on welding a tank that's previously had gas inside?

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          #5
          Originally posted by Panici View Post
          Did you end up welding the tank back closed?
          Any tips on welding a tank that's previously had gas inside?
          I welded both of them closed. Honestly, once it's been open like that for a few days and it's been wiped-out there's *zero* residual vapor and you can't even smell it, let alone create an explosive environment. It's worth it to just get a new tank for all of $275, too.

          I opened the tank with "thin-cut" dremel blades which are 1/32" thick so there wasn't much gap to fill. For pressure testing I made some fittings to seal everything up and kept pressure below 1psi.



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          Last edited by hoveringuy; 05-29-2023, 09:00 AM.

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            #6
            That seems far more complicated than just adding a surge tank.

            RISING EDGE

            Let's drive fast and have fun.

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              #7
              Originally posted by Digitalwave View Post
              That seems far more complicated than just adding a surge tank.
              It is, but it isn't. Unless you have an early tank where you can co-locate the surge tank with the fuel filter, there's no easy way to install a surge tank without external lines, bulkhead fittings, etc, and then you still have a second pump. Surge tank is still a great solution, just not for me.

              The advantage to this approach has been stock form and reliability, and I get the added benefit of not having a bunch of fuel sloshing around in turns.

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