I did a search and looked for it in the tech section but can't seem to find a thread on this issue anywhere.  I filled up my bike this morning and when I got to work the tank was leaking from the bottom by the seat.  It is a 2002 with 225xx on the clock...modified but nothing done to the tank.  It was -40 degrees this morning and I'm wondering if I'm just missing some kind of overflow or if I'm not going to have any gas when I get back to the shop.  Am I just blind or???

There are only two factory issued openings in the tank - the filler neck where the cap is and the opening at the bottom where the petcock is attached.

If the leak isn't from the gasket between the petcock and the tank, or from the hose between the petcock and the carb, I'm thinkin' you've got a hole in your tank. Or the gas cap isn't on tight.

Ok...got home and have just now stopped working on the bike...hopefully I got it fixed.  Ended up taking the tank off and found that the whole mount at the rear of the tank had started to crack and was actually pulling holes in the tank where the spot welds were.  So I threw some JB weld on it to hold it in place (and thought I covered the hole).  Let that set then checked to make sure I got rid of the leak...which I hadn't.  So I covered it some more with JB weld and let that set.  Still leaking so I had to put some perma-seal liquid gasket (I was out of JB weld at this point) on it and I'm going to try to get some sleep and check it again in the morning.  I was kicking around the idea of putting a different tank on the bike anyways so I guess here's my answer.  The guy I bought my bars from has a 883 Sportster tank that I'm trying to see if he'll sell me on the cheap...then I guess I get to tackle fabing up some mounts for that this weekend.  Then will have to find an auxiliary speedo also, might run without one for awhile since they're not required here in SC.  Guess it wouldn't be a bike if there wasn't always something new that "has" to be changed or "has" to be worked on...at least that's what I tell the wife.  

NAPA used to sell a two part Play-Doh type epoxy for car gas tanks that went on the outside after thorough kneading to mix them. The main thing is getting the surface clean...without making sparks, of course. Be sure your rubber grommets are all there and installed correctly. Flexing is not good for sealing.

I don't think JB Weld or any other stick on stuff is going to work for very long even if you get it sealed for now. My suggestion is to drain the tank , flush it with water and then take it to a radiator repair shop and let them fix the crack. Those guys are pretty good a sealing cracks in stuff like this. I've had auto gas tanks repaired by radiator shops a few times.

Then make sure when you reinstall the tank on your bike you have all the rubber cushions that Suzuki put on there when it was new.

I really don't think your tank is worth fussing with too much - unless it has some special paint job you are trying to keep.  Replacement tanks are pretty cheap on eBay.

The hard part about trying to fix this tank is that the cracks and leaks could be located behind the welded on mount - and you can't access those areas without first cutting the mount off so you can get behind it.

Thanks for all the advice guys!  That's why I joined the site.  On a side note (kind of).  I was talking to a buddy of mine who I occasionally ride with, he has a '74 Honda CB 750 (sweet looking ride, all original).  I was telling him about my problems with my tank and mentioned the idea of putting a Sportster tank on in replacement.  He got all offensive and said he'd rather put pedals on my bike than put a Sportster tank on it, amongst other things.  It got me wondering...why the disdain between HD riders and non-HD riders?  We all ride for the same reasons right?  So why on this green earth does putting a Sportster tank on my bike make it such a bad bike???  Just a wee bit confused.  I mean he went to the point of saying he wouldn't ride with me anymore...it's all water under the bridge for me because I'll ride everyday whether he wants to ride with me or not I'm just boggled right now...a bike is a bike.