Possible tank leak search help needed.

[beeryboats]

Hi all,
I posted a help needed on this issue before, but now I have a photo. I got the header tank out without leaking a drop of fuel even though it was half full. The secret you ask? All the inlets and outlets were plugged solid! And I removed the semi-rigid rubber fuel line on the right side. At one time the builder opened the hangar door to find a puddle of fuel and an empty R/H wing tank. Since then it has set for ten years. So now I'm looking for a leaking tank problem. I've been told to do the balloon on the cap vent, but take a look at the photo and tell me if those fittings look ok to you.
Thanks,
Jay

[cap01]

pretty nasty looking but probably didn't leak a tank of gas on the hangar floor .
I'm not a fan of a poly / galvanized combo. if it needs taken apart , Kitfox has some permatex 9a that works really well , a little messy but works well for sealing the fittings in the fiberglass tanks . just be careful not to over tighten and strip out the threads in the fiberglass when you put it back together .

[jrevens]

Hi Jay,
That looks like a nylon barbed hose fitting. Nylon can get relatively brittle over time & is much weaker than any metallic fitting. Even baring that, I don't think it's a good choice for a fuel fitting. I would personally use brass or stainless steel, or even anodized aluminum instead of nylon. I would use the same metal for the threaded bushing. That's just my personal opinion based on standard aircraft practices.

[Wheels]

Yup, replace that plastic/poly stuff. Your fuel system is the lifeblood of ignition. ignition is the lifeblood of compression … lifeblood of spinny thing in front … or sometimes in back, but ultimately lifeblood of thrust, which is usually how we overcome gravity and … have fun and stuff.
I replaced mine by purchasing the new ethanol resistant tanks and replacing the entire fuel system. Probably NOT necessary if the rest of the system is healthy, but mine was not. I had two power failures related to fuel in 250 hours, so I did the whole thing. I'm not a fan of unsanitary fuel or oil delivery systems. Fix it or walk. Flying isn't an option unless you like to gamble.

[beeryboats]

I know, pretty stupid. I'm going to change over to brass. Is that bushing a finger strainer going back into the tank? I also wonder why they don't put inline filters between the tanks and header tank?

[beeryboats]

Ok, to answer my own question, yes there is a finger strainer. Mine however, has a large hole in the end. It was very hard to photograph, but see for yourself. I'm pretty sure that's a generic item. Aircraft Spruce maybe?

[Dave S]

Beeryboats,

Filters in the line between the wing tanks and header tanks??.....at least in my case I experimented with that.....tested it and found the filter could cavitate if air hit the filter..... to get the flow started again it was necessary to pressurize the wing tank ...after my experiment on the ground I ripped the filters out and stayed with the fuel system design specified in the Kitfox manual before taking to the air.

Other's milege may differ depending on specific components (filter or line size); however that was the experience I had.

Sincerely,

Dave S
KF 7 Trigear flying
912ULS Warp drive

[beeryboats]

That's why I post my questions to the group. So many had issues with the older tanks, I was thinking if you had one tank that was going bad you could isolate the bad tank with a filter while the other good tank was free to flow. Versus both good and bad fuel going to the one filter and shutting down the engine.
I had to settle on Gates/Napa brand barricade hose today as the Goodyear brand is not available. The Napa guy was nice enough to print the specs so I could look at them before I pulled the trigger on the purchase.
As I need to place an order with Spruce anyway I got to thinking about all the sump drains that will need to be rebuilt now while all the fuel is out.

[Wheels]

Ok, to muddy the waters, I do have glass visible filters in my line from tank to header. I also have a vent line to each tank. I fly it and can visually see what's happening and have run several dozen tanks of fuel through the system. The extra vent solved a problem with excess fuel being overboarded through the single vent into a single tank and giving me an asymetrical fuel load in flight.

You probably can over filterize (I just made that up) but to leave out essential filters is a no no. Bing carbs don't like dirt. (check the forum)
I have an inline filter at the tank, a gascolator, finger strainers for the big stuff in the tank, and whatever else comes organic to the carbs and fuel pump if anything.
I used the in line filters because of the old sloshing compound that was coming off my tanks. Now I have new tanks and thats not an issue but I like seeing if there is any crud in my fuel before it gets to far down stream.

[beeryboats]

Ok, so I'm not crazy on the filter idea. I don't see any sloshing compound in my tanks from the filler, but I plan on endoscoping the tanks tomorrow. I'm still not understanding your issue with only the one vent though.