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Thread: Has anyone pressure tested a fuel tank?

  1. #1
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    Default Has anyone pressure tested a fuel tank?

    I bought an old mod IV before I read about the fuel tank issue in the earlier kits. Mine has a stain on the right D window from a fuel leak that I at first attributed to old brittle fuel lines. It's been setting for 10 years. Had I known about the tanks, I may have kept looking. Will these old tanks take a couple psi so I can check for a crack?
    Thanks,
    Jay

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    Default Re: Has anyone pressure tested a fuel tank?

    Never did anything like that, but I would be very reluctant to try with much pressure. Two pounds over 100 square inches (10" X 10") is 200 pounds. Maybe if you put fuel in and then put just a bit of pressure in the tank. If you have the ram air tubes on your fuel caps, you could hook a hose to the vent and blow into it while watching the top of the tank to see if it looks like it's swelling to much. Jim Chuk

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    Super Moderator Av8r3400's Avatar
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    Default Re: Has anyone pressure tested a fuel tank?

    I have pressure tested the fiberglass tanks via the "balloon" method.

    Band a plain balloon over the fill neck. Plug the other ports and pressurize only with "lung" pressure. Measure the balloon diameter and wait a period of time and measure again or look for leaks with soapy water spray.
    Av8r3400
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    Senior Member jdmcbean's Avatar
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    Default Re: Has anyone pressure tested a fuel tank?

    Lung pressure ONLY! Av8r3400 is correct.
    John McBean
    www.kitfoxaircraft.com
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    "The Sky is not the Limit... It's a Playground"

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    Default Re: Has anyone pressure tested a fuel tank?

    Hmmm. Wish I had one of the blood pressure pumps. That would make it super easy. I could just tap into the vent line and give it a couple pumps. Or should I replace the rotten fuel line and hope for the best? The builder used that hard plastic split wire loom that's corrugated for protection on the fuel lines. The rubber line escaped half way out the cover and the line is now a figure 8 cross section and hard as a rock.

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    Default Re: Has anyone pressure tested a fuel tank?

    Amen on minimum pressure for leak test. I've heard of deaths with only a few psi and a tank rupture.

  7. #7
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    Default Re: Has anyone pressure tested a fuel tank?

    I agree, I watched a high pressure CO2 tank take flight one day. I didn't know I could run that fast. The guy that popped it was lucky he didn't loose any fingers.

    AV8, help me out here, I'm trying to figure out your procedure. If I plug all the openings except the fill cap, which I cover with a balloon, how do I pressure the tank? Also, where the heck do you get a balloon that fits over the filler neck? Do you mean you put a balloon over the caps vent/pressure tube?

    It's been one of those days, please forgive my thick head tonight.
    Jay

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    Super Moderator Av8r3400's Avatar
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    Default Re: Has anyone pressure tested a fuel tank?

    If you can get one (or several) of the big party balloons they might fit over the fill neck. You are right, I meant the pitot vent on the cap.

    Of course one of the other lines will need to be the "mouth piece" to pressurize the balloon. I used a sheetrock screw to close that tube...
    Av8r3400
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    Senior Member t j's Avatar
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    Default Re: Has anyone pressure tested a fuel tank?

    Balloon and soapy water used to check for leaks.
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    Tom Jones
    Classic 4 builder

  10. #10
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    Default Re: Has anyone pressure tested a fuel tank?

    That's what I thought. I just wonder if the seals under my filler caps will hold a seal at this age. I guess I'll find out!

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