Possible tank leak search help needed.

[kitfoxnick]

I have glass filters that can be seen thru the turtle deck. These filters come apart to clean, and have a fine mesh filter. I like being able to see if I'm getting any crud out of the tanks. I would not recommend the use of paper filters.

[Micro Mong Bldr]

Only 1 vent has the potential to cause uneven flow, you have to plumb the vent to both tanks if you have only 1. Probably easier to just have 2.
Cheers,
L

[beeryboats]

L,
I don't know how that could happen when both caps have air pressure tubes pointed forward. I noticed that the left tank has what looks like a poor mans fuel gauge. It's a piece of 1/4" clear tubing that goes from the bottom to the top of the tank. But the builder also left large sections of the end of the tank unpainted with fuel level marks in felt pen.

I took a couple videos with my endoscope of the inside of the tanks. I don't know what to think. I see what appears to be large pieces of epoxy that I can move by thumping the underside of the tank. And on the left side I also see what looks like an area of flaking paint. But that could be just epoxy sticking up too. I was looking for fuzzy fibers and didn't see anything like that at all. I think I'm going to go with in-line filters, at least for a while, and see what comes out of the tanks.

[Wheels]

Ok, John Mcbean, slap me if I use the wrong word again. Vent line or Return line are two distinctly different components to the fuel system.
When you add the rotax recommended return line to your system, you are giving a route for excessive fuel to be "returned" to the tank. The fuel pump is capable of delivering more fuel than you will use during operations and the return line allows the excessive fuel to go back to the tank rather than be pressure pumped into a carburator that doesn't need it and cant burn it all.

As the fuel returns to a single point, EXAMPLE, left tank, the left tank ends up with more fuel than the right tank. (DUH) On a long flight, say 3 or more hours, it is not abnormal to see one tank at 1/4 full and one tank nearly empty. So I simply added a y connection at the return line from the header tank. I put in a return to the left and one to the right tank. Now excessive fuel is symetrically pumped back to my tanks and I don't see the difference in my fuel load during a long flight. I did this to a set of brand new Kitfox supplied ethonol resistant fuel tanks before I installed them. My Mechanic "friend" used all brass fittings.

Fuel Vent/ is the forward angled tubes on top of your wing and yes it allows ram air to lightly enter your fuel tank to keep possitive pressure in your fuel flow while simultaeneously giving your fuel system a breath of air to keep VACUME from occuring in the system. (Put your finger over a straw and suck through the other end, nothing moves. Open the "vent" and you have flow.)
If you turn them backward, you will create a vacume problem and life can become interesting in a short time, or it could end in tragedy. So, to recap, Vent is air, return is fuel. whatdoyathink? I am unsure about the condition of your tanks but it sounds bad, can you send pics?

[beeryboats]

Thanks for the info, but I'm wondering if we have the same set-up. I have the 582 Rotax two stroke, and from what I've been able to see so far I have a feed line to the header tank from each wing and a header tank vent that goes back up to the right tank. I've been able to trace the fuel system up to the firewall so far, but I just got things moved around so I could get the cowling off. From what I saw yesterday I see the fuel line go to the fuel shut-off, which broke when I turned it, then to the gascolator, then to the fuel pump, then two lines go into the mess of stuff around the carbs.
I'm touching anything else until I can get some photos taken. But I see nothing like a return line. I work at a diesel shop and I'm very familiar return fuel systems. I see nothing like that.

[cap01]

you are correct , you don't have the same set up for your fuel system . my model IV book makes no mention of a fuel return in the system . seems that the fuel return is to remedy starting problems associated with a hot engine where the fuel in the lines on the engine is heated causing the engine to flood for the next start

[Wheels]

Yep, Wheels here is flying a model IV with a 912, not a 582. Someone out there has a clue, today, its not me. But, its a pretty logical system, you wont need a NASA resume to figure it all out. Do check your tanks, they sound like they need to be replaced or reworked. would love to follow this thread and see pix.

[cap01]

wheels is correct , if there is stuff lifting in the tanks you are asking for trouble

[beeryboats]

I'm not sure it's lifting. It looks like globs of resin that dripped down and never adhered to the tank bottom. It's hard to tell from the camera image, but the biggest looks about two inches long. Or maybe the size of your pinky finger. I wonder if I could tape a probe to the camera so I could poke and push at things in the tank? I wish I had an idea of what the internal structure of the tanks looked like. I assume there must be a baffle of some sort. I was going to ask the folks at Kitfox about the tanks when I ordered a new header tank, but I guess they are all at Oshkosh. Lucky stiffs!!!
I gotta work.

[kitfoxnick]

In my original mid 1990's 13 gallon tank there are two baffles. My tanks also had large globs of resin all over the place and was from the original layup. Don't confuse this with the kreem separation issues. The Kreem is tan in color, and the resin is more of an amber color. The new tanks from kitfox are of much better construction then the tanks supplied in then mid 90's.