Fuel cap vented or not ??


Information and questions on GL1500 Goldwings (1988-2000)
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curtm
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Fuel cap vented or not ??

Post by curtm » Sat May 19, 2018 8:05 pm



When i take my fuel cap off it is under vacuum, suppose to be like that or is suppose to be vented ???
Curt



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Bluewaterhooker0
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Re: Fuel cap vented or not ??

Post by Bluewaterhooker0 » Sat May 19, 2018 9:56 pm

Under vacuum, or under pressure ? I would think pressure would be much more common than vacuum. Engine heat will generally heat the fuel, causing it to vaporize and generate pressure. The cap, to my knowledge, is vented both ways, to certain vac and pressure specifications. If you are seeing vacuum, I'd try cleaning / soaking the cap in Seafoam as a solvent, and blowing out passages with compressed air. Is the vacuum causing a drivability issue ? What motivated your question ?

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wingdings
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Re: Fuel cap vented or not ??

Post by wingdings » Sun May 20, 2018 2:15 am

Hi - there saw your post - May I ask you if your wing is cutting out at all - ?? view this vid -see if it fits your problem that you are having there ... ??





and take a look at this too !!! -





it maybe that your fuel cap maybe sticking there - hope this helps - best regards too !! - :D :D :D :D :D

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terryt
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Re: Fuel cap vented or not ??

Post by terryt » Sun May 20, 2018 3:29 am

I have the same on my 89 when I release the fuel cap. you get that hiss. It never caused a problem when riding. I don't have that type of cap with the spigot on the top to vent it on mine.

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Erdeniz Umman
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Re: Fuel cap vented or not ??

Post by Erdeniz Umman » Sun May 20, 2018 3:48 am

terryt wrote:
Sun May 20, 2018 3:29 am
I have the same on my 89 when I release the fuel cap. you get that hiss. It never caused a problem when riding. I don't have that type of cap with the spigot on the top to vent it on mine.
If that sound is because of vacuum it may cause power loss, probably you are experiencing pressure built up inside the tank due to vaporization.

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terryt
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Re: Fuel cap vented or not ??

Post by terryt » Sun May 20, 2018 4:38 am

Erdeniz Umman wrote:
Sun May 20, 2018 3:48 am
terryt wrote:
Sun May 20, 2018 3:29 am
I have the same on my 89 when I release the fuel cap. you get that hiss. It never caused a problem when riding. I don't have that type of cap with the spigot on the top to vent it on mine.
If that sound is because of vacuum it may cause power loss, probably you are experiencing pressure built up inside the tank due to vaporization.
Thanks for reply. even though I have not notice any power loss I have just looked at my fuel cap. I removed the rubber gasket and noticed 4 vent holes around the edge. sprayed a load of wd40 in there then checked the centre hole and it seems there is a diaphragm in there that was stuck just freed it and will check when I have given it a run

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WingAdmin
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Re: Fuel cap vented or not ??

Post by WingAdmin » Tue May 22, 2018 4:19 pm

The cap has a vent that will resist both vacuum and pressure - to a certain point. When running and fuel is used up, it will allow some air in, but there will be some vacuum - so when you open the cap to fill up after riding for a while, you'll hear air rushing in. If the fuel heats up and the air expands, the vent will allow air to vent, to prevent the tank from overpressuring.

If the fuel cap gets clogged, it can allow too much pressure or vacuum to build up.

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curtm
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Re: Fuel cap vented or not ??

Post by curtm » Fri May 25, 2018 5:47 pm

No there has been no ill affects from the cap situation, other than the crappy gas mileage, getting 33mpg, seems bad
Curt



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