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Discussion Starter · #1 ·
I have a 2002 Sprint ST that I just picked up and I'm having fuel leak issues. The fuel was found to be coming out of two hoses leading to the underside of the bike. I'm assuming they are vent/overflow hoses, but don't know for sure. I clamped off the tubes for the night just to not have dangerous fumes in the garage and still got a couple of ounces when unclamping this am. I ran the bike and let it sit a bit after with seemingly no problems, then when going out to check, found more dripping from the hoses. I had not run the bike but had reclamped the hoses and found later today that gas was oozing out of the fill cap!! I used the key to open the fill port only to find it was under quite a bit a pressure and fuel sprayed out quite a bit. Is the tank supposed to be pressurized on this bike and if so, should it not lose pressure when not running? It has been 102+ degree days here in Oklahoma and I know my plastic gas cans in the garage are swelled like ticks. The tank is not overfull, but definitely close to full. Do I have a faulty fuel vent or something? Has anyone heard of this? Any help is greatly appreciated.
 

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Most likely you need new fuel connectors (quick release).

There is a thread about it on this page and many others a quick search will find lots of information about this.:)

Welcome to the forum:)

Cheers
DaveM:AustralianFlag
 

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Discussion Starter · #3 · (Edited)
I don't see a link to the post you are referring to and I appreciate the help, but if the post refers to the broken bits on the connectors, I don't think this is my problem. Fuel is clearly coming from the two vent lines that go from the tank to below the frame (one for tank and the other for around the filler port). I think the integrity of the system is fine, but curious why the tank is under so much pressure and causing fuel to come out of the hoses (or out of the fill port if I clamp the hoses). It may just be a too full tank with expansion because of the extreme temps in the garage, but it seems the vents should vent the gasses and not actual fuel. I plan to look tomorrow when I have time, but wondering if anyone else has seen this and knows something in particular to check. I've never had the tank off and I'm hoping it is as easy as my Ducati as it could just be lifted and held with included prop when the seat was off. I'm also planning to check the recalled bits to see that the plastic connectors are now the upgraded metal and check to see if everything else looks good. I also plan on blowing a bit of compressed air back through the vents to see that they are not clogged unless someone on here tells me that's a bad move for some reason (damage to pump or something). Just wondering if anyone else has noted the problem. Besides the obvious cost in the loss of the gasoline, sitting in my garage and generating so many fumes and vented gas is a fire/explosion hazard, so a bit of a concern to say the least :) Again, thanks for the previous post and appreciate any additional info. Thanks..
 

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The drains ( vents) on these models are KNOWN to be crappy and block up, compressed air,WD40 and or fishing line, then spray em every so often with WD..........:)
 

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Discussion Starter · #5 ·
With fuel coming out of the drains, it almost seems they are working TOO well... lol.. I can't tell from the outside which is which, but I'm wondering if the main tank vent is not blocked and causing tank to pressurize with the heat and push fuel out of the vent for the filler port. I hate having to take the tank off of this thing as it seems from other posts that it can be problematic and things can get broken, but I have to figure out what's going on with this thing before I have a fire in my garage. I'm hoping I can figure it out.
 

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Sounds to me like your tank is really full. I fill my tank as full as I can, and don't have this problem. So, thinking out loud, .... I agree, your vents are working :D. Your plain tube should be on the rear barb, and the tube with the tipover valve should be on the front barb. I'd check to see if the tipover valve is installed corectly, as in not upside down. I'd also check to see that it's working properly. Aside from that, I would hate to think that there is a small leak/hole in the vent line somewhere inside the tank.
 

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Discussion Starter · #7 ·
Good info, thanks. Less fuel on the deck this morning by far, so I'm leaning towards overfill with extreme heat/expansion. I also, out of necessity, had to use that damned ethanol gas the other day (out and everyone either had 87 octane only or 91 with ethanol). I know it expands more due to the ethanol. I usually never use it anyway (my Vette also requires the premium petrol with no ethanol per manual). As far as how full, she was on the side stand and filled her nearly to the rim. I used to fill my Ducati like this and never had any problems. For now, I'll keep the fuel level down and keep an eye on her. I'm putting aside funds for a "major service" from the dealer anyway since I just purchased the bike and know little of its history, I'll mention this to them then and have 'em take a peek for me. Whew, on a side note, the dealer estimates $700-800 usd for major service? Seems kind of expensive, but probably worth it in the end, yes?
 

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I fill mine to the brim, set it on the sidestand, and haven't had any problems like yours. So I do think you have something going on.

As far as the service goes, search the forum here. There's lots of good information. Look at the maintenance section at the top of the forum page. There are maintenance schedules listed, along with how to's. Look at the "blogs" section over on the left column of this forum page. Go to the technical section. Lot's of good info there. Just have to do some looking.
Get a manual, and get a feel with what you would be comfortable doing yourself. Aftermarket fuel filter and oil filter will save you money right off the get go. Whatever you can do for yourself will save you money.
 

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Discussion Starter · #9 ·
Took her for a ride and burned some fuel off. Stopped to see my girl at work for about 30 minutes and when I came out, more fuel on the deck from the vents. Took her home and went to pull her in the garage and sure enough about a drip every two to three seconds from just ONE of the vent lines (assuming it is the main tank vent and not for the fill port. I'm going to let her cool then gently blow some compressed air up through the vent and into the tank to clear the line, but my thinking is this probably will not help because since fuel is dripping out, it must be clear, unless the one for the fill port is the one that is clogged. Very frustrating and difficult to work on in 100+ degree weather to be sure. Looks like I may have to pull the tank after all.... Perhaps in the cooler part of the evening. Open for any other things to check that have not been mentioned. Thanks for all of the help. Man, I need a service manual for this thing for sure.... Probably break the bank though... lol..
 

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Discussion Starter · #10 ·
Went back out into the garage once it had cooled down outside a bit to find that the glass bowl I had placed under my vent lines was nearly full of gas. It's about a normal sized cereal/salad bowl, at least 10 ounces. So, obviously, my fuel leak is not from being over-filled. Someone out there that knows these machines pretty well, can you hit me with some theories? As I understand it, instead of a petcock, there is something on the bike that senses vacuum and allows fuel to flow, then acts as an automatic petcock turning the valve off when there is no vacuum.. Is this at all correct? If so, what is/are the device/devices/mechanisms that cause this to happen? I'm trying to come up with a list of devices that could possibly be at fault and try troubleshooting or removal and replacement. I'd like to have a few things on hand before I remove the tank, but being unfamiliar with with new bike makes it a little tougher. I'd just take it to the dealer, but we only have one, they are backed-up for three weeks and they will likely charge me a fortune for what logically seems as though it must be something simple/small/easy to fix. Anyone out there experience this or know the fuel system well enough to speculate on a culprit? Assuming the lines are open since I'm getting the gas pouring out.. What's next? Thanks again for any help.
 

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If you open your cap and look, you'll see a small round cup on the rear right of the opening. Look at the cap and find the mating plug to that cup. It seals the gascap to the vent, and the tank vents thru the 2 little holes in the underside of the cap, thru that mating plug and cup. Now, run your finger along the underside of the lip of the tank and feel how the tank is molded around the hose from that cup. It goes thru the body of the tank, to the bottom where the hosebarb is connected. Here your vent hose and tipover valve are located.

There is no vacuum operated petcock like on a carburated bike. There is an internal electric fuel pump that feeds the fuel injectors.

Pull the forward part of your rear bodywork off the right side of the tank and look at the two small lines connected to the tank just below the outside edge of the tank. If gas is leaking out of the forward small line, the one with the tipover valve, then you have a problem with the vent line in the tank. If gas is leaking from the rearward line/barb, then it's leaking thru the rain drain for the area under the gas cap. I am really hoping that you see fuel leaking from one of the larger diameter hoses with the plastic fittings. Those are your fuel lines, connecting to the fuel rail and returning to the tank.
A while back someone had a problem with a tank. They took pictures with a borescope, and it showed how the vent and drain tubes were encapsulated in the tank's construction. I'm not sure how you could fix something like that. If it's any consolation, I did see a couple of used tanks on ebay in the $75 US range.
There is also a coating that some folks have used on the inside of their tanks to protect them from the effects of ethanol on the plastic. I don't remember what the stuff is called. Hopefully, someone familiar with it will add to the thread.
 

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Discussion Starter · #12 ·
Thanks for all of the good info. I look forward to pulling her apart tomorrow after work. No matter what, I'm sure it's fixable and I can figure it out thanks to the good help on here.
 

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Be careful too, believe it or not, some of these Bikes plastic tanks can and DO 'deform' when off the Bike and are a pain in the arse to refit...................mine certainly 'expanded/flattened out' and took two people to refit..... :(
 

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Discussion Starter · #14 ·
Okay, took a look at the vent hoses. I blew through them and they seem to both be open. Hard to tell if they are supposed to flow more, but they DO appear to be open. I tried running a guitar string down the vent hole in the cap, then through BOTH nipples the exit the bottom. The string would only go about 10 inches either way and would not actually exit the other side through any port. I'm wondering if there is not some kind of filter in there or maybe just a tight bend the string can't negotiate. Anyway, they seem open. Next, I took a look at the tipover valve. It was not directly vertical as it was and not sure if this matters. Also wondering if the bleeding thing is even on correctly, so someone please chime in and help if you know the answer. What is the correct orientation of the valve supposed to be? I know it should be vertical, but if I blow through the valve, which way should the check valve be BLOCKED from airflow if the bike is on its side? Seems to me that if I am blowing air AWAY from the tank or "down" the line, it should STOP allowing airflow if I turn the valve on its side (simulating the bike on its side) so that fuel will not flow out.... Is this thinking correct? Also, any possibility that the valve is bad and causing a leak or that it not being completely vertical in orientation could cause a leak? Or maybe if if is installed upside down? If the rear line is open (the one from the "overflow" area of the filler port) should air blown into the front nipple only come out of the tiny hole that gets mated to the cap? I feel as though I'm being thick, but can't for the life of me figure out that if the rear line is open up into the tank, why I'm getting fuel coming out of the front one if that line ONLY goes to the tiny hole that mates to the cap. Would this indicate that the path INSIDE the tank is broken and allowing fuel into this line or something? If so, shouldn't I be able to pass a guitar string/wire all the way through but end up in the tank instead of out of the nipple? Man, I'm so confused. Am I making this harder than it should be?
 

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Can you put a hose on your front vent nipple, block the vent cup up by the cap, and blow thru the hose and witness bubbles in your tank? This would indicate a failure of the vent hose traveling through your tank.
 

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Discussion Starter · #18 ·
Connected a hose to the front nipple and blew into it with cap open (of course, but trying not to miss anything). Air blows quite freely through the little nipple until I cover it with my finger, then builds pressure as you would expect. I can see no bubbles in the tank nor can I hear any bubbling in the tank. It seems the line is functioning as it should and there is no break in integrity through the tank..
 

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Discussion Starter · #20 ·
Update.... Well, special thanks to my new best friend CharlieS who was kind enough to give me his number and hash this out with me on the phone. No matter what happens, much thanks to you and if I can ever return the favor, feel free to ask. As for the bike situation...

First, let me say there was an error in the post below and was corrected! The fuel was coming out of the REAR nipple under the tank and NOT the one with the check valve. This is what led us to believe that the check valve side was blocked, therefore forcing fuel under pressure back through the other side and out the rear nipple. At least, this is the theory. With that in mind, read on....

Both vent lines were open with no problems and there was no leak on the vent tube inside the tank. I DID notice that my tipover valve was not completely vertical and when "blow" testing it, proved very sensitive to any horizontal positioning, which at least means it does its job folks. I went out and purchased some new lines to be sure they were of good integrity and to ensure they would reach to the proper exit point under the bike. I've re-oriented the valve to be completely vertical, buttoned her up and went for a spin. She's now back in the garage with my trusty glass bowl under the vent hoses. I'll check her again in the morning to see if she has leaked any fuel and report back what I find. If there is no fuel, she might just be fixed. If there is any fuel in the bowl, my next thing is to completely remove the valve, run a straight line and check her again. If I get no fuel then, it's probably the valve, if I DO get fuel.....well, to be honest, I'll have no idea what to check next and without further ideas or inputs, I'll have to make an appointment at our ONE dealer and wait about a month to get her done. I'm really hoping she is fixed. If she is, then perhaps this little thread will serve to help someone else in the future. Wish me luck guys!! I would sure love to just RIDE this girl! After all, I just got her :)
 
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