Leaking fuel, what gives?

[vesku]

Came back from holiday in Berlin and was going to ride to summer house for Midsummer festivities. Only to find out that, motor running, fuel leak from under the gas tank of my -85 100rs! A couple of weeks ago I had the tank off cos I changed the steering rod. Haven't noticed any leaks since, tho. I haven't checked yet, but do anyone have any clue where that fuel come? It leaks from the left side somewhere in the middle section and only when motor running. I had filled the tank very full before holiday, could it just be some excess coming out?

[frankenduck]

If it's leaking in the left middle then many times it's the welded seam being corroded by water over the years.  If you take the tank off you might see some bubbling of the paint to confirm this.

[orforester]

I slower my leak down to a seep or weep by sealing the inside with JB Weld.  Not sure why it didn't stop it completely, but it is manageable now.  This winter I will see if I can find someone to weld it up. 

My thinking is that if I take the gas cap off and the fuel sender unit out, given a month or so, it shoudl be safe to weld or fix better.  JB weld may be a problem for welding, but time will tell. 

Good Luck

Bob

[Scott_]

...... It leaks from the left side somewhere in the middle section and only when motor running. ......

I'd check your fuel line connections on the underside of the tank. Sounds like you have one of the fittings loose, or fuel line has cracked and started leaking from moving the tank.

[frankenduck]

The left middle thing is used usually caused by water causing corrosion.  Since the side stand is on the left and water is heavier than gas that's the seam that gets exposed to the most water.  (If there is any.)

Good idea to take the tank off and clean it out annually.

[Rick G]

If it is leaking only when the engine is running then it is most likely to be the hose fitting not being tight or a cracked hose.

[Opus]

Had same problem with my 82 Goldwing. Found small hole in bottom of tank. I tried JB Weld and other stuff but it only got worse.
Ended up replacing the tank. It still could be a hose or tank problem though even if it only does it when running.
Heat from the radator and/or motor will cause gas to expand and force the gas out of any hole it can find.
Try running the bike with the gas cap open and see it the problem remains. (you did say it only happens when it is running right?)
Ether way get it fixed ASAP. I know it is cool to have flame shooting out the back of your ride, but this kind can get you killed if it gets hot enough...

Just my 2 cents

Opus!

[vesku]

thanks everybody for your kind answers. I finally got to check it properly and it turned out that one of the hose fittings had come loose. I tightened it and everything is just fine now!