Pressure build-up in gas tank?




#1
I have a 2008 busa and i just bought and installed a new keyless gas cap.
My bike runs great and everything but when i stop to get gas and un-screw the gas cap, there seems to be an awful lot of pressure build up in the gas tank, i can hear it go "swish" from the pressure when i remove the gas cap....Is this normal?
 
#2
I just googled it and i guess it is normal..... Before when i had my original lock-gas-cap i never heard any pressure in the gas tank when i un-locked gas cap to fill up..

It is no big deal when you have a lot of pressure in the gas tank if anyone else is wondering.
 

rubbersidedown

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#3
I would want my tank to vent as the manufacturer intended. But hey,if yer happy with yer googled answer...:thumbsup:

Myself,I modified my aftermarket fuel lid to vent.

To each his own...party on Garth.:super:

RSD.
 

rubbersidedown

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#7
Not a good thing, venting problem can cause your tank to deform, i have seen it.
Plus air must replace used fuel or...fuel starvation.
Plus,if pressure builds too much..where does it go,what happens.:dunno:

There is also nothing like having fuel spray you when you go to top up.

But hey...if you and the "Kawi Guys" are happy. :google::stoopid:

My lid mod took 30 seconds. Less time than it takes to.... grab a link and respond to a thread.:rofl:

RSD.
 

rubbersidedown

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#8
Guy here said thet the ethanol caused over pressure in a Ducati and burst the plastic tank, split open....
he'll be fine Strom...it was researched and diagnosed with :google: and "The Kawi-Guys".

Why am I such a mean ol bastid. ???


Cause its fun.:laugh:


Excuse me,I have some gas pressure to go get rid of...:flush:

RSD.
 
#10
shouldn't happen...tank has a vent line and its obviously blocked or nipped somewhere...usually happens when lowering the tank after doing work under it.
+ve pressure puts you at risk in so many ways....opening the cap releases a cloud of flammable gas which could easily be ignited innocently by a nearby smoker etc....also pressurises the seals on the tank which aren't intended to withstand pressure...only for holding back the fuel.
-ve pressure from a lack of air getting into the tank as fuel is used could cause fuel starvation running problems as well as making the fuel pump work harder( think of it like drinking a bottle of beer without letting any air in as you swallow )....gets so far then no matter how hard it tries it can't pull the fuel from the tank.

A properly assembled and maintained bike shouldn't have either pressure situations.
 
#11
I am a member over at kawasaki forum also, heres what they say about pressure build-up in gas tank....I am not worried but thanks.
er6n gas tank pressure buildup? : KawiForums.com Kawasaki Forums: Kawasaki motorcycle forums
Into motorcycles for 40 years this summer, the busa is my 16th bikes, hondas-kawas-yams-suzs and harley, dont tell me it's normal because it's not, if your er6n is whistling to you it's because it's telling you that he have difficulty breathing normally. Now if your bike build pressure and doesnt whistle, lets just say that i would not drive your bike.
 
#17
shouldn't happen...tank has a vent line and its obviously blocked or nipped somewhere...usually happens when lowering the tank after doing work under it.
+ve pressure puts you at risk in so many ways....opening the cap releases a cloud of flammable gas which could easily be ignited innocently by a nearby smoker etc....also pressurises the seals on the tank which aren't intended to withstand pressure...only for holding back the fuel.
-ve pressure from a lack of air getting into the tank as fuel is used could cause fuel starvation running problems as well as making the fuel pump work harder( think of it like drinking a bottle of beer without letting any air in as you swallow )....gets so far then no matter how hard it tries it can't pull the fuel from the tank.

A properly assembled and maintained bike shouldn't have either pressure situations.
Now does anybody know where this vent line is? Mine has been whistling since I got it from the original owner who had no idea why it was doing it. My mechanic didn't seem too concerned with it when I told him about it. I have noticed as the tank empties that bugger start blowing pretty hard, so hard that if I'm laying on the tank I can smell the gas while I'm on the freeway. I don't think it's a big deal though because cars build up pressure too.
 

rubbersidedown

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#18
No idea I bought it used off an org member. Its an after market threaded lid
Un do the lid. If you see a tiny little set screw with an allen head on the flat part...we are in business.

Take the lid surround off the tank,depending on the type,some bolts actually hold it on,some are there for looks. Take a small allen key and remove the set screw,sometimes there 2. DONT do this on the bike,why? Because when you take out that set screw(s) a little spring and ball bearing are going to fall out. Leave those things out,set screw,spring,ball bearing and re-install the lid. GTG.

RSD.
 

rubbersidedown

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#19
Now does anybody know where this vent line is? Mine has been whistling since I got it from the original owner who had no idea why it was doing it. My mechanic didn't seem too concerned with it when I told him about it. I have noticed as the tank empties that bugger start blowing pretty hard, so hard that if I'm laying on the tank I can smell the gas while I'm on the freeway. I don't think it's a big deal though because cars build up pressure too.
take the seat off,remove 2 bolts at front of tank,use prop in hump to hold up tank. At the bottom back of the tank you will see your hose. Un kink,and lower tank as you look undereath to make sure the fuel line/vent tube etc does not get kinked again. GTG.

RSD.
 

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