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Discussion Starter #1
I've been watching this site for a while, and if it's been posted, please forgive me, but;

Every time I open my fuel cap, there's a great deal of pressure behind the cap. Today, after riding, I turned the lock on the cap and it practically shot open.

I've only had the bike a few months, it's been nothing but cold outside since I've had it... and with nearly 2000 miles, I think the cap has been under pressure every time I've opened it.

Anything to be concerned about?

Thanks!


:)
 

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Implosion warning

The pressure SHOULD be venting via the cap. There are two one way valves in the cap, one going one way, the other going the opposite. They both vent through that little rubber grommet near the hinge which leads to a hose (or on California bikes to a charcoal canister). If pressure is building up something's blocked. If the other valve blocks your tank WILL IMPLODE as it cools. I've had one tank implode on my 900SSie twice before I found the problem. It turned out that the grommet sometimes deforms when you close the cap, blocking the hole in the cap. Easy fix was to cut a small vee in the grommet.
My advice is to find the cause of the blockage before your tank pops. Hope that makes some sense.
 

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Discussion Starter #3 (Edited)
Thanks, I'll have a look at that grommet. Kinda sounds like a warranty issue on a brand new bike, no?

I've noticed no unusual fuel consumption, and AFAIK it's always been positive pressure.


(side note: Kudos to the admins of this site! The 'suggested related topics,' across to the other forums, which I may not frequent as much, is a REALLY NEAT feature! *pretty slick technology, too* Excellent!)


:)
 

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I recall discussions on the ST Yahoo group about the connections of two hoses in the gas tank getting mixed up. Does this ring any bells? Sorry I cannot recall any more, but I am a techo dunce.
 

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Discussion Starter #5
mmkay... I looked at the grommet, it looks fine, not mushed or anything. Mates up to a little hole in the fuel cap door. Anybody know where a check valve would be?

Now I'm even more sure it only holds positive pressure. I filled it up hot, and after cooling overnight, there was zero pressure (in or out) behind the cap. But when I start it and get it warm again, and open the tank... PFFFFFT!!


Thanks.


:)
 

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Discussion Starter #6
Found it!

The large vent hose under the tank was being pinched by one of the fuel pump assembly bolt heads. The hose bears the mark of the bolt head. I twisted it slightly and made sure it was routed clear of that bolt head.

I think that's the end of the story...



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when working, it should "sing" a bit when parked as the pressure equalises.....


Doc
 

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DocMV said:
when working, it should "sing" a bit when parked as the pressure equalises.....


Doc
Afterall, these bikes are Italian divas!
 

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I was going to mention the hose under the tank but I see you found it.
That was pinched on mine and caused a tank "implosion".
It's real easy to pinch so it's a good idea to monitor it carefully everytime you lift the tank and then set it back down.
 

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Discussion Starter #10
smegtheprez said:
It's real easy to pinch so it's a good idea to monitor it carefully everytime you lift the tank and then set it back down.
I hear that! I'm thinking it was that way before they 'prepped' it, when I took delivery. It's been up and down several times since, and I didn't think to look at it.


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Discussion Starter #11
Update: 2 weeks ago, it started doing it again, and sure enough... the hose was pinched again, but this time against the top of the head.

All of the pressure must've been taking it's toll on the gas cap... because after I unpinched the hose and finally found where it's SUPPOSED to lay... the fuel cap was weeping in my lap while riding. No prob through the Aerostich, but the smell was quite strong... so a couple nights ago... I decided to disassemble the fuel cap and check it out. I'm SUCH an idiot.

When I removed the final screw, the filler door flew into tiny pieces like Pandora's pocket watch - pingngng... complete with plunk, plunk, plunk, pieces falling into the full tank. (don't even say it, I'm an idiot.) Tiny springs and a ball bearing the size of a gnat shit. It was that sinking feeling of knowing, "this is going to be expensive."

Well, thanks to my little magnetic stick 'getter' and the ferrous nature of all the pieces... every piece retrieved, (did I mention, I'm an idiot) and after three hours of trial and error, all of the pieces - present, accounted for, and working properly. The closure piece, with the rubber ring around it, is pressed into the opening with 4 springs... I guess the pressure in my tank had that closure piece squished down and stuck that way.

One great thing I learned, when working with tiny metal pieces, try to do it where your nose is more than 3 inches from an open gas can... and dopple every teenie-tiny piece with grease, so they stick in place while you assemble.

Anybody need their Rolex fixed? (by an idiot?)



It works great now, nice and smooth, with no farts.

Now I hope THAT's the END of the story.


:)
 

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LiquidSilver said:
Now I hope THAT's the END of the story.:)
Won't do that again, will ya. Good job!
 
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