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Discussion Starter · #1 ·
Hey guys, I installed a keyless gas cap a few months ago. I was out in the garage today and I wanted to see how much gas was in it and upon unscrewing the cap there was a VERY noticeable pssssst sound. I thought that maybe it was just because I hadn't opened it in about 2.5 months so I didnt pay any attention. I turned the bike on for about 5-10 minutes and when I opened the cap again, it gave me the same psssssst sound, like there was alot of fume buildup.

The cap I have is supposed to be vented, and its the same make that I have on my Honda which doesnt have this issue. Is this normal or is it something I should investigate further?

Thanks
 

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where does it vent to? could you post a picture of the cap and the filler hole?

the stock cap vents through two tubes that exit the bottom of the tank down to the bottom of the bike.
 

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The fuel caps on our bikes are not vented. The fuel tank itself has a vent line that comes out the bottom. Make sure that both rubber hoses that come off the bottom of the fuel tank are free and not pinched or kincked. One of the lines is the vent line and the other is a drain to prevent water puddling around the filler cap. Both are important so you might as well check both of them.
 

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Discussion Starter · #7 ·
Ill check those lines too. Thanks.

The cap does block the drain hole. I assumed that was the vent.

Im guessing the vent/drain holes on the tank are hard lines within the tank and then go into rubber hoses under the tank, correct? If the hard lines are clogged, how would I go about clearing that?
 

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Correct and use an air compressor to blow back through the lines but be careful you don't want to break something by putting too much air pressure on it. I can't imagine how an internal breather line could have gotten plugged though. The only time I've ever seen that was a bike that sat for years with water in the tank and the breather line plugged up with slime and rust. The other thing that frequently plugs the breather line is a bad carbon canister but since you are in VA I doubt you have one since they are a California model only item.
 

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Discussion Starter · #9 ·
Correct and use an air compressor to blow back through the lines but be careful you don't want to break something by putting too much air pressure on it. I can't imagine how an internal breather line could have gotten plugged though. The only time I've ever seen that was a bike that sat for years with water in the tank and the breather line plugged up with slime and rust. The other thing that frequently plugs the breather line is a bad carbon canister but since you are in VA I doubt you have one since they are a California model only item.
My bike actually is a California model. Ive been meaning to remove all that crap though.
 

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Have you had the tank off recently? Check for a pinched vent line.
 

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Discussion Starter · #12 ·
Have you had the tank off recently? Check for a pinched vent line.
I have not, but I have been meaning to replace the fuel line with the newer version.

Well if you have a carbon canister then that is likely your problem It's real easy to test. Run the bike for a little while and then pull the hoses off the charcoal canister. If you hear a sucking sound that's your problem.
Thanks, Ill check that out this weekend. Whats a little while? 10-15 minutes?
 

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Go for a short ride if you can. If not really all that needs to happen is a temperature change so if for instance you have a heated garage if you open the tank and close it and then take it out in the cold the tank will develop a vacuum without a vent. Or just over the course of the day if it's cold in the morning and then warms up the tank will develop pressure if you first vented it by removing and installing the cap in the morning.

Honestly I'd just get rid of the charcoal canister no matter what. They are nothing but trouble on bikes.
 

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I had a 99 Sprint st and the drain /vent lines clogged up from corrosion. it was a common problem. removed the side cover and the rubber tube. then I took a small drill bit and spun it up the tube with my hands only. it cleaned the blockage out
 

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Discussion Starter · #16 ·
I ended up pulling the carbon canister off the bike along with the valve for it. The canister itself didnt appear clogged as it dumped a nice amount on charcoal on my floor.

I havent had any odd issues with the cap since. It appears to be venting properly. Im keeping an eye on it however.
 
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