HELP: Fuel Tank Drain Tube leaking

[RangerRay]

New to the site; hate to bring a problem with me the first time to the table, but...The bike had sat with an empty tank for several months. I got it up and going, and filled up with gas, and now the "fuel tank drain tube" is leaking fuel- a steady drip of one drop every 3 or 4 seconds. This tube runs from a fitting in the bottom of the tank and exits down next to the radiator over flow on the bottom on the right side of the bike. What could cause this? My initial reaction is that there is something wrong with the tank. After I removed the tank, the fitting where this tube was connected still drips. Any ideas? My worst fears are that the tank has a leak allowing this to happen, but I would certainly like to have someone else's better educated guess before I pop over $500 for a new tank! Thanks for any help.

Ray

[Daveontheedge]

Are you talking about the fuel shut off petcock? If you remove the fitting is there an o-ring or gasket under it? My guess would be o-ring has dried up if there was/is one in there.

[guntherrex]

I think you mean the overflow tube. You probably overfilled the tank, and/or the petrol expanded because of the engine heat, getting pushed out of the overflow. It should stop by itself, just be sure not to smoke next to it

[a_morti]

TheRe are two hoses under the tank whose purposes aren't immediately obvious. The thin one allows air into the tank to stop it vacuum locking. The thick on allows water down from the fuel cap when it rains. Both are metal tubes through the fuel tank. If those tubes rust and get a hole then fuel can leak through and out. Not good nes as you can't block the drain or the tank fills with water if it rains. Can't block the vent as it'll air lock.

Ideally you want to get in the tank and slip a rubber hose over the tube. Not sure how else you can do it.

[RangerRay]

Thank you for all the replies! Morti, I think you are right; it is most certainly the large tube that is leaking fuel.  What I'm not yet sure of is whether or not I overfilled the tank...I don't THINK I did, but...I have the tank off the bike right now, so I think my plan is to drain some of the fuel and see if fuel still drips out of the large tube from the bottom of the gas tank.  My thinking is that if removing some of the fuel works, I overfilled it and that is the cause of my problem.  If it does not work, I think I have to assume that the tube running thru the tank is corroded and allowing fuel to leak out.  Conceptually, I can see where the solution of covering the tube on the inside of the tank would work; in practice, I don't see how it could be done- it would be like arthoscopic surgery.  At that point I can see 3 possible solutions: replace the tank ($$$), keep it a fair weather bike (not that hard to do- I'm a fair weather biker, and it's not my only bike), or some sort of tank treatment.  I've read about some of those, but never paid really close attention.  I guess I might have to do more research!  Does anybody see any holes in my assumptions/logic?

Ray

[a_morti]

Wonder if you could put a smaller bore plastic tube inside the pipe? Maybe grease it up first? The old trick like when threading mains cable and you draw it through with string migh be handy.

[rigwit]

if the pipe has corroded internal,all is not lost drain tank run an exhaust in to it- ie you want exhaust fumes going into tank then you can either measure the pipe length going into tank from where it is welded to underside either cut it off there and put a thinner piece of pipe in and get it brazed/welded or soldered in.

Tank will be safe to be welded as exhaust fumes kill any petroleum vapours that would make it go BANG.

[RangerRay]

Again, I appreciate all the replies.  I confirmed my suspicions that the tube is indeed corroded inside the tank.  I did this by attaching a hose to the outlet at the bottom of the tank and blew thru it; not only did fuel blow out of the hole that is at the 9 o'clock position of the gas cap, the fuel that was in the tank bubbled.  So as to the fixes; I can't see any reasonable way to work inside the tank without doing major surgery (for which I am neither equipped nor inclined)- the only real access would be from the gas cap or the hole underneath after removing the petcock, both of which are quite small.  My intent now is to try my luck at feeding a piece of fuel resistant tubing inside the existing metal tube; the thought being that if it is tight enough, it will keep fuel from leaking around it.  The problem being that if it is tight enough to seal the leak, it will be difficult to feed thru the twists of the existing tube.  My fall back solution will be to plug both ends of the tube.  This is simple, but I will lose the tank's ability to vent for overfilling, and run the risk of water getting in the tank.  The overfilling one is easy to avoid (just don't over fill it!).  I'm a bit more at the mercy of fate with respect to the water issue...but It's probably a safer bet here in California that it might be for you British folk!  I will update with my results when I have them, so that if somebody else finds themselves with the same situation, they will find something when the search!  Again, thanks!

[rigwit]

Quote "My intent now is to try my luck at feeding a piece of fuel resistant tubing inside the existing metal tube; the thought being that if it is tight enough, it will keep fuel from leaking around it."

If you do it that way to get a good seal you could try a brass nipple hose tail and file it down so it expands the tubing against the exposed tube (original outlet).