Odd Noise Fuel Venting?


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johnfliesagain
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Odd Noise Fuel Venting?

Postby johnfliesagain » Mon Apr 18, 2016 7:53 pm



This is the first day of a warm weather trip. drove about 40 miles.

When I got home, with the engine off I heard a really weird noise. sounded like air escaping from a balloon... remember being a kid and filling a balloon and then pinching the opening so there was this high pitch...vibration / noise?

At first I thought it was the rear shock filling... maybe I thought the button got stuck. But no that was not it. And it was periodic and repetative.

So the engine was off. Parked slightly uphill. side stand. It would last for about 5 seconds, then stop for ?? 20 seconds then go again.
I opened the door to the fuel fill and it was slightly louder.

I opened the fuel tank and then there was a pressure release from the cap. O K I thought its done. No noise. Well wrong. after a couple of minutes started again. Popped the tank cap and pressure release again . hmmph? What more pressure! Well its warm out say 82*F. and the bike was hotter of course, so maybe all that heat was causing the gas to vaporize more...? no?

Should I be concerned or is this normal to a Goldwing.


John in Baltimore
A proud owner of a 2000 1500SE
:D Did I mention it was a Free Gift from a co-worker?

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Bluewaterhooker0
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Re: Odd Noise Fuel Venting?

Postby Bluewaterhooker0 » Mon Apr 18, 2016 9:27 pm

I haven't personally experienced this problem, but have read a few comments about it. The fact that it is making noise indicates it is venting, which is good. It's supposed to. The general heat exposure, in addition to the engine heat rising to the tank area, especially after shutoff, will certainly generate some vapor pressure in the tank as the gas heats up. Fuel cap issues seem to be addressed on this forum by soaking the cap in Seafoam for a period of time, to loosen up and dissolve any deposits that might be clogging, or partially clogging the vent mechanisms. I would try that, maybe overnight, and reinstall to see if the issue goes away. I don't know that it is a safety or performance issue as long as it does vent. But I suppose the sound of your bike 'farting' every time you stop could be an issue.

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johnfliesagain
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Picture of one of my Triples Yamaha xs750 '79 at Timonium Bike Show 2015

Re: Odd Noise Fuel Venting?

Postby johnfliesagain » Tue Apr 19, 2016 5:07 pm

Bluewaterhooker0 wrote:I haven't personally experienced this problem but have read ( always of course..no not me it was the dog.) But I suppose the sound of your bike 'farting' every time you stop could be an issue.


Well it's not quite like that....its a high pitch whine that turns into a lower note...not the flatuent sound .

I was concerned that the fuel pump could have been running with a faulty relay... but it wasn't And I had full battery power this morning. didn't notice it tonight with a full tank of gasoline vs. last night with only about 1 gallon that would vaporize easily.(I guess)
John in Baltimore
A proud owner of a 2000 1500SE
:D Did I mention it was a Free Gift from a co-worker?

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Bluewaterhooker0
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Re: Odd Noise Fuel Venting?

Postby Bluewaterhooker0 » Tue Apr 19, 2016 9:03 pm

johnfliesagain wrote:
Bluewaterhooker0 wrote:I haven't personally experienced this problem but have read ( always of course..no not me it was the dog.) But I suppose the sound of your bike 'farting' every time you stop could be an issue.


Well it's not quite like that....its a high pitch whine that turns into a lower note...not the flatuent sound .

I was concerned that the fuel pump could have been running with a faulty relay... but it wasn't And I had full battery power this morning. didn't notice it tonight with a full tank of gasoline vs. last night with only about 1 gallon that would vaporize easily.(I guess)


I'm in the air conditioning business. If gasoline behaves like refrigerant and virtually all liquids, and I believe it does (based on some guys 'law', I think it was Boyle), the vapor pressure will be the same regardless of the amount of gasoline vs vapor space. The pressure is temperature dependent, the temp of the liquid. One thing that might effect it is the quantity of liquid and the time it takes for the increased volume of gasoline to rise in temperature. More gasoine, longer time to rise in temperature. Less gas, less time to rise, less volume, less mass. So, more pressure due to less gasoline volume....up to a point (eventually, even the larger mass will equalize to the ambient temperature or engine temp, if exposed long enough).
I was joking about the flatulence. I figured it was more of a squeal.

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WingAdmin
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Re: Odd Noise Fuel Venting?

Postby WingAdmin » Tue Apr 26, 2016 10:14 am

Bluewaterhooker0 wrote:I'm in the air conditioning business. If gasoline behaves like refrigerant and virtually all liquids, and I believe it does (based on some guys 'law', I think it was Boyle), the vapor pressure will be the same regardless of the amount of gasoline vs vapor space. The pressure is temperature dependent, the temp of the liquid. One thing that might effect it is the quantity of liquid and the time it takes for the increased volume of gasoline to rise in temperature. More gasoine, longer time to rise in temperature. Less gas, less time to rise, less volume, less mass. So, more pressure due to less gasoline volume....up to a point (eventually, even the larger mass will equalize to the ambient temperature or engine temp, if exposed long enough).
I was joking about the flatulence. I figured it was more of a squeal.


You're 100% correct. I was going to write almost the same answer, but you've already done it.

Both the high pitched squeal and the flatulent sound can be the gas cap venting pressure. The previous suggestion of soaking the gas cap overnight in Seafoam is a good one, and will usually clean up any venting problems.

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Bluewaterhooker0
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Re: Odd Noise Fuel Venting?

Postby Bluewaterhooker0 » Tue Apr 26, 2016 3:47 pm

WingAdmin wrote:
Bluewaterhooker0 wrote:I'm in the air conditioning business. If gasoline behaves like refrigerant and virtually all liquids, and I believe it does (based on some guys 'law', I think it was Boyle), the vapor pressure will be the same regardless of the amount of gasoline vs vapor space. The pressure is temperature dependent, the temp of the liquid. One thing that might effect it is the quantity of liquid and the time it takes for the increased volume of gasoline to rise in temperature. More gasoine, longer time to rise in temperature. Less gas, less time to rise, less volume, less mass. So, more pressure due to less gasoline volume....up to a point (eventually, even the larger mass will equalize to the ambient temperature or engine temp, if exposed long enough).
I was joking about the flatulence. I figured it was more of a squeal.


You're 100% correct. I was going to write almost the same answer, but you've already done it.

Both the high pitched squeal and the flatulent sound can be the gas cap venting pressure. The previous suggestion of soaking the gas cap overnight in Seafoam is a good one, and will usually clean up any venting problems.


I may print that up and frame it. According to my wife, I've NEVER been 100% correct about anything.




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