fuel leaking mystery...?
 

i have an occasional fuel leak coming from one of the hose bundles right next to the oil filter on the left side of the bike. the fuel varnish is thick on the chin fairing, and splattered all underneath the oil pan/ belly of the engine. this has been going on since i dropped it on the left side at a low speed, mostly cosmetic damage. so theres the mystery leak and i believe its running rich by the smell of the exhaust, and hard starting. so anyone know what this could be?.....i just sterilized/degreased the whole bottom part of the engine so i can trace the drip precisely. but its intermittent. so any info will be appreciated. i will update this post as i find out more. hopefully i can fix it myself before i go into a shop and drop some cash for my stupidity.
:confused:
justin

Most likely you have a float sticking in the carburetor bowl or have trash in the fuel line resulting in the float not being able to completely close the fuel supply off when the bowl is full (float floats and pushes up and closes off the fuel supply)

The line are from the carbs bowls and act as overflow run off to keep the excess fuel from flooding the cylinder.

Suggest adding in-line fuel filters, removing the bowls and cleaning out the debris and carefully removing the float and cut off valve and making sure there is no debris on it.

This should do the trick.

Note: if this were an older bike that didn't use vacuum fuel shutoff on the petcock the sucker would probably empty the tank sitting in your garage.

Item 23 is the Float Valve and Item 4 is the float. If trash is on top of 23 the valve cannot close all the way when the float bowl fills up thus the fuel flow cannot be regulated and must go somewhere, which is out the bowls overflow tube and down to the chin spoiler.

Attachment 30827

thumper you are awsome:D!!
i was heading down that path and you clearly connected all the dots for me. so i'm jumping into the carbs as soon as i can! thank you!
i will keep you posted in case it is something different!

i'm fuming....literally!!
 

ok something different!
---EDIT---
after cleaning the lower part of the engine free of grim and varnish from the fuel leak, i have found that it is coming from the fuel BREATHER tube!!?? and is seems to start leaking when the sun hits it first in the morning.....like the heat creates pressure and starts to force it out!!........so what should my next step be to verify this is def. it guys?

also thumper, you said in your original post that the problem could be fuel overflow from the float bowls...i am not aware of any lines coming from the floats?? so i couldn't see what you were talking about originally??

thanks all!

.........

EDIT---its the breather tube

I would say you run the risk of gas coming out around the top of the tank and flowing down the sides if you plug that hole. I'm not that smart, but since you said it is when the sun hits it, might it be the gasoline and air in the tank expanding and causing gasoline to seep out around the top seal? It happens to the can of gas I have in my shed for my mower.

........

EDIT- the breather tube is leaking, the drain tube is dry.

My thoughts were that it may be evaporating and condensing on the thicker metal (stays cool longer) at the filler and by sort of capillary action or the pressure buildup it is drawn out. Half a tank may cause this worse than a full tank. This probably isn't possible, so someone prove me wrong.

doesn't sound right to me?

ok seems i have screwed up between the two...it is NOT the drain tube, but the BREATHER tube, and for sure this time. i test poured some gas into the top of the tank where the lil drain is, and i came out the opposite tube i was suspecting, so for some reason fuel is leaking out of the breather tube. i can see a bit of vapor coming form the tube while the bike just sits also.
i haven't a clue how to remedy this.

Might wanna check you're O-ring seal on the actual cap itself. Vent tube shouldnt be getting any fuell to it unless you open you're cap (pressure), or over flow the tank when filling up. You're seal is probably letting fuel through.

you are thinking of the drain tube (that little drain to the left when you pop the cap).....i'm talking about the breather tube which is internal inside the tank, only fumes/vapor should come out of this thing. i talked to a tech at a shop and he said there was a one way valve inside the tank that lets extra pressure release when the tank gets hot???? but maybe he doesn't know what hes talking about either.

c'mon guys someone has to have a clue as to what this could be!? 125 views?

can you trace the leaking tube back to it's source/connection? does it connect to the petcock? which nipple?

fuel is leaking from the fuel tank breather tube. and i don't know why. it is intermittent and seems to happen when the sun hits it in the morn. and heats up the tank abit.....i can't figure it out....this was after a low speed drop on the left side about 35mph......the previous posts have abit more info.

OK sorry about sending you off on a wild goose chase with the floats and bowls. I work on so many bikes that i forgot that our chickenhawk didn't have carb bowl drain hoses like a lot of bikes do.

Well if this is the bigger of the three lines that run down to the chin spoiler i seem to recall the big one is the tanks breather tube as you mentioned.

Strange that fuel would be coming out of it. I am kind of stumped as well.

If you consider it like a gas can this is just a vent for gas pressure that builds up as you ride and heat in the tank. Just like a vent on a typical 5 gallon gas can vents off the pressure.

The strange thing is how it is getting fuel in it. I wonder if something somehow got bent inside the tank when it fell over and now the vent tube inside is in the incorrect place.

i will try to get out to the garage and take a closer look at my spare track day tank i have. It is empty and i may be able to determine where the actual internal tube goes to inside the tank where the big line attaches to.

Ok Justin,

I just took the gas gauge sending unit out of the bottom of my spare track day tank and i have verified the following.

Big tube from the bottom of the tank to the chin spoile is the fuel over flow line and only goes from the fuel cap area to the chin spoiler. If i use the mighty vac on this larger hose i can verify it in no way connects to theinside of the tank. Only way fuel will come out of it is if you over fill the tank of the caps o-ring is leaking fuel and it is spilling out past the o-ring and into the over flow.

the smaller breather line goes all the was to the top of the tank via a small size tube inside the tank. It in no way connects to the outside of the tank in any other location than the hose connection.

All this being said another posted suggested that the tank o-ring may be bad on the cap. That is possibly the issue if the fuel is coming out of the bigger hose (Over flow).

If only from the smaller tube then i suspect something is broken inside the tank in relation to that vent tube line that goes all the way to the top of the tank. If the tank is low on fuel you can open you cap and shine a flash light in there. Looking from the fron tof the tank the metal vent hose will run from the rear, past the sending unit up to the top of the tank.

hope this helps....

very much appreciated! i heard i could get the tank coated inside to seal tiny holes and seam breaks?

after all my research, it is def. inside the tank. thanks for everyones input with this! i found a bike shop that will epoxy coat the inside of my tank to seal it for around $70.....i figure i should give it a shot before i drop $550 on a new tank. i will post again after i have this service done to see if its worth a shit.

My son just had a similar problem with his TL 1000 S Suzuki. He epoxied around the leak inside and then coated his tank (creme, I think). He soaked a wad of epoxy in a jar of gas a few days to check it out...very stable stuff. If you do end up getting a new tank don't ever pay $500!!! I'm surprised these leaks develop. Doesn't seem like much stress and my sons tank was real clean inside. It's as mysterious as electricity or women!