Motorcycle Tank Leaking Through Overflow Constantly

[DRider]

Hey guys,

Got a strange problem that I'm not sure how to fix. My '00 GSX600F has a constantly leaking overflow line in the tank itself, that is, the overflow directly from the tank, not from the carb. I noticed there was always a small puddle of fuel beside the bike whenever it had been stood, and upon investigating, there is a constant dripping of fuel coming from the overflow port on the bottom of the tank. Not a lot by any means, but still there, and it's absolutely destroying my fuel efficiency, just due to the fact that when the bike is stood overnight, it's obviously still losing fuel.

Taking off the overflow tube, it's coming directly out of the overflow line from the tank; I figured that it would possibly be a crack around the line which I could seal up, but it's not a leak, so much as the bike is literally acting as if the tank is constantly too full. Not sure if this stops at all as the tank gets lower in fuel, though I do know that it still leaks out while the bike is running also.

Really hope those last two paragraphs make sense... basically, I've got no clue what is causing this, or how to fix it, but it's wrecking my finances from having to replace fuel much more frequently than usual; wondering if anybody can help.

Thanks guys.

 

[lupin]

Has to be pressure in the tank to cause that. When you open the fuel cap does air rush out?

It does sound like a blocked breather hose.

 

[dandoolittle]

Have you tried simply turning fuel tap off when you're not using it?

 

[DRider]

Howdy guys,

Thanks for the replies. I've looked into my problem a bit further and found that the breather hole at the petrol cap is not blocked. From the petrol cap, with the cap open obviously, I could actually see the pipe that goes from the breather hole near the petrol cap and runs down to the exit of the breath pipe at the bottom of the tank. I put my finger over the exit section of the pipe, blocking it off, and used a straw to blow air into the breather tube. Lots of little air bubbles came out into the petrol in the tank, so it seems to be the overflow pipe itself (that runs through the tank, not the rubber hose section) that is somehow damaged and probably has a pinhole or two in it. No idea how that would have been caused. I also have no idea how I can fix it.

The only solution I can think of is that I possibly cable tie some rubber around the end of the overflow pipe, basically stopping anything from flowing out of the tank if it's overfilled, or, in this case, if the pipe is damaged and leaking. Not sure if that would cause any issues however; not entirely sure what the overflow pipe does, aside from releasing excess fuel around the cap. Think this is a decent idea? At the very least it'll definitely stop the fuel from leaking, and would save me a bomb on costs.

Also, dandoolittle, sadly the issue isn't with the fuel tap, and as it is, my fuel tap is a vacuum based tap which only has ON, RES and PRI positions, no off. Good suggestion in any case.

If somebody could let me know if blocking off my overflow pipe would cause issues?

Thanks guys.

 

[dandoolittle]

Well the overflow to my knowledge also doubles as a breather

I'll ask a couple of menchanic mates for you