1100 Fuel Cap making noise after about an hour ride

Joined
Oct 2, 2013
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125
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Bedford,Texas
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92 ST1100
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#8753
I searched and didn't find an answer to this, but my search foo is not great. After about an hour ride today in 80 plus degree heat, I got home and pulled into the garage when I noticed a noise. At first thought someone was using a blower outside,after I closed the garage door I realized that it was coming from the bike.

I popped the cap and released the pressure and the noise stopped. Is this normal on the bikes? I checked the hoses and they are clear and not pinched. Is the cap maybe defective and not venting properly?
 
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Quite normal to hear those farting sounds. Somewhere in there is a pressure relief valve.
 
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I think it's normal. Mine does it too. As long as the hose isn't filled with crude at the end ( near the swing arm) , I wouldn't be concerned. BTW, it seems like the pressure relief in the cap works in both directions. Remove the small hose and blow into the small port, and you might hear the noise.

BTW, The first time I heard the noise in the garage, I thought there might have been a squirrel in the garage farting, but it turned to be the gas cap relieving pressure - surprising, indeed !!
 

Rossi

R.I.P. - 2014/08/28
Rest In Peace
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Nova Scotia, Canada
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7236
Yes, mine (ST1100) moans and groans sometimes. I think it's the filler cap venting at the right rate to cause a harmonic frequency.

EDIT. Jim Van posted while I was typing.
 

ST1100Y

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so does mine, pressure or air relief valve kicking in, the tank pressure feeds petrol to the carbs unlike other bikes that are gravity fed ,well the cx500 was,

nothing to worry about its normal
 
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so does mine, pressure or air relief valve kicking in, the tank pressure feeds petrol to the carbs unlike other bikes that are gravity fed
Ummmm, no, the fuel pump feeds the carbs.;) Let's not confuse anyone new to the 1100 here.
 
OP
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tmds3
Joined
Oct 2, 2013
Messages
125
Location
Bedford,Texas
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92 ST1100
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#8753
OK I think I found the solution(maybe), I noticed that if I put the cap on where the arrow is pointing towards the front of the bike the cap doesn't make any noise, but, if it is pointing in any other direction it will. I wonder if it has something to do with the way it is built, maybe aligns perfectly if arrow forward and slightly off if it is not pointing forward?
 
Joined
Mar 12, 2006
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226
Location
Brewerton, NY
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ST1100/ST1300
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949
Fuel tank cap farting is perfectly normal on the ST1100. The noise you hear is the double check valve reliving tank pressure when the fuel is very warm. It has nothing to do with which way the cap arrow is pointing, etc... You should still have a good look up into the cap and see if it's varnished with age. It may need to be serviced / cleaned out. ST-Riders.net has the procedure in the ST Archive's Of Wisdom. One thing I can strongly recommend if you do take it apart and clean it, is DON'T use carb cleaner. Too aggressive. It will ruin the rubber valve.... Mineral spirits, kerosene, etc...
 
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