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Discussion Starter · #1 ·
Anyone experience fuel coming out of the overflow/breather nipple under the tank while under braking?? Thats when it seems like its happening, while braking. I plugged 1 end with my finger and blew low pressure air thru the other end and there wasnt any air bubble or noise from inside the tank, my thought was that maybe the part of the breather tube that runs inside the tank rusted thru and sprung a leak. I just tanked up and I know I didnt overfill it, matter of fact I think I underfilled it.
 

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I'm curious too . Same thing happened to me last week. Don't have any pipe connected to my breather nipple either. That's how I bought it.


Zee
2000 Triumph Thunderbird Sport
2010 BMW F650GS
 

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I don't have a hose on there either, the only thing I can think of is maybe its a faulty fuel cap.
Had the problem on my Adventurer, vacuum lock in the tank and over pressurization causing leaks. It was the fuel cap, I rode around with the cap loose for a while and symptoms went away. I drilled a few holes in the underside plastic of the cap and have been fine since.
 

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Discussion Starter · #6 ·
Had the problem on my Adventurer, vacuum lock in the tank and over pressurization causing leaks. It was the fuel cap, I rode around with the cap loose for a while and symptoms went away. I drilled a few holes in the underside plastic of the cap and have been fine since.
Curious to know why after all these years its happening now. Before I go drilling holes in it, I can see me screwin this up royally lol, where exactly in the plastic part did you drill, below the threaded part right?
 

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The flat plastic outside of the threaded part. In between the snap ring and the threads. Ride around a few days with your cap loose to make sure this is the issue or take the cap off and check it.

Put the cap threads in your mouth and breathe in, you should be able to breathe in through the cap but not out.
 

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Discussion Starter · #8 ·
I took it out for a good ride and with the cap loose no fuel leaked out. On your Legend, dont you already have little holes drilled where your describing on your cap cause mine does? I suppose I could drill a few more, but at least now I know what the culprit is. I'm waiting for the cap to dry off a little before I do the breathing test lol! Watch a cop will drive by and think Im huffing!
 

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Discussion Starter · #9 ·
I was able to inhale but not exhale so i'll do what you said in the 1st place and ride it a few more days with the cap loose and see what happens.
 

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The cap which I drilled did not have holes, the cap on my TBS and Legend have holes and I'm able to breathe in and out of them.
 

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Discussion Starter · #11 ·
So I should be able to breathe in and out on mine then since there are holes. I can only breathe in on mine not out.
 

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I would rather have any sputtering of excess fuel coming out of the overflow/vent fitting, through a hose, and onto the ground, than have it coming out the tank cap and dribbling down my paint and onto my knee, which is what would happen with me if I went to drilling vents in the cap.

IMHO, Triumph designed the cap with a one-way vent so that the tank can draw in replacement air as the fuel level drops. Excess fuel or tank pressure is meant to vent through the vent fitting, which IIRC is plumbed right up to the top of the tank by the filler neck. If you are getting more than an occasional sputter out of the vent when the tank is fullish, you may well have a leak in the vent plumbing inside the tank. My guess is that that would be hard to diagnose and even harder to rectify.
 

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Discussion Starter · #13 ·
Looking at my fuel cap and looking at 1 I bought on ebay I noticed that part of my cap is missing, I imagine its floating around in the tank now. I also matched it up with my gf's T-Bird 1600 cap which is identical to it and yup its missing some parts. 1st thing that came to mind when I noticed the leak was the vent tube inside sprung a leak, had that happen with my Daytona 955, so I took low pressure air and plugged 1 side to see if I could see or hear any bubbles, I couldnt. Its not solid proof there isnt an issue inside but im looking at that prior to the leak I had just tanked up, so maybe taking the cap off and on this last time finally did it in, with help over time from ethynol I'm sure.
 

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I also matched it up with my gf's T-Bird 1600 cap which is identical to it...
Not saying it's so, but be careful. Even though they may look identical, unless they have the same part number, there might be subtle differences (like in the venting).
 

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Discussion Starter · #15 ·
Not saying it's so, but be careful. Even though they may look identical, unless they have the same part number, there might be subtle differences (like in the venting).
Same part #T2400597. Now I just hope the 1 I bought on flebay is the same, looks like it but??
 

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Guys we're making this too damm complicated. Drive around with you tank 1/2 full with your gas cap loose to rule out the gas cap. There should be a check valve somewhere in the tank vent line, it lets air out but if the bike is tipped over it'll stop the fuel coming out. Find it remove it and see if you can move air through it.

I drilled holes in my cap because it was an easy and inexpensive fix. Never had any issues like fuel leaking or excessive venting and making my garage smell like gas.
 

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Discussion Starter · #18 ·
I have it. Took it off when I put K&N pods on cause with out the chrome covers to hide it it looks like ****e lol, thats what I get for appearance over functionality. Been riding it now for a few days with the gas cap loose and so far no leakage. I never drilled out the cap and my garage does not smell like gas! Although I do need to tank up again so we'll see what happens.
 
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