Gas cap suction pressure and tank noise is not normal


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1potter1
Posts: 9
Joined: Sun Oct 14, 2012 6:17 pm
Location: Overland Park, Kansas
Motorcycle: 1999 GL1500

Gas cap suction pressure and tank noise is not normal

Post by 1potter1 » Tue Sep 01, 2015 4:45 am



When I was figuring out my hot hard start issue I've seen few post with folks replying the suction or pressure from the gas cap after a ride is normal or the whining noise from the gas tank trying to vent is normal.
If you have this issue your probably having problems with hard starts when the bike is warm do the the pressure on the fuel tank.
Pressure on gas cap is not normal and the red line coming off the top of the gas cap is a designed vent tube to aliviate these issues.
What I found happens when this issue occurs is the rubber diaphram in the gas cap has a small hole in the center to allow venting buts gets a little off center and does not allow proper venting.
If you look on the tank side of your gas cap you can see the orange rubber diaphram with a small hole in the center, if you don't see the hole take a small screw driver and pull the small hole in the diaphram to align with the center of the vent tube to allow venting of your gas tank.
if this doesn't solve your issue also check the vent line for kinks and clogs.
I would suspect this issue alone has caused the
many failures to the petcock from extreme pressure on the the petcock diaphram.



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dingdong
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Location: Oklahoma City
Motorcycle: 1976 gl1000
1993 gl1500
2004 NRX1800 Rune

Re: Gas cap suction pressure and tank noise is not normal

Post by dingdong » Tue Sep 01, 2015 7:25 am

Good info. Never heard this before. Thanks!

Tom
Tom

John F. Kennedy would be impeached by todays liberal Democratic socialist party.

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BENJEE2112
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Location: Port Charlotte, Florida
Motorcycle: 1995 1500i INTERSTATE
THE ONE STYLE "WITHOUT" REVERSE ((Danggit))

Re: Gas cap suction pressure and tank noise is not normal

Post by BENJEE2112 » Sat Feb 23, 2019 9:44 am

Thanks 1potter1. I've been smelling gas after rides since I bought my 95 1500. Is there a way to test the petcock? It was stalling yesterday. I thought I fowled out a plug. Until I pulled over and opened the cap. Then it ran like a top. I cleaned the cap once last month. Seemed to be okay running wise but always smell gas after rides. Is there a preferred liquid to use for cleaning it. Last time I used
W-D 40.

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dingdong
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Location: Oklahoma City
Motorcycle: 1976 gl1000
1993 gl1500
2004 NRX1800 Rune

Re: Gas cap suction pressure and tank noise is not normal

Post by dingdong » Sat Feb 23, 2019 2:06 pm

BENJEE2112 wrote:
Sat Feb 23, 2019 9:44 am
Thanks 1potter1. I've been smelling gas after rides since I bought my 95 1500. Is there a way to test the petcock? It was stalling yesterday. I thought I fowled out a plug. Until I pulled over and opened the cap. Then it ran like a top. I cleaned the cap once last month. Seemed to be okay running wise but always smell gas after rides. Is there a preferred liquid to use for cleaning it. Last time I used
W-D 40.
There is a pressure vent in the cap. It can become clogged. Soak cap in Seafoam overnight and it should clear. WD40 is not really a solvent.
Tom

John F. Kennedy would be impeached by todays liberal Democratic socialist party.

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wingdings
Posts: 316
Joined: Mon Feb 10, 2014 12:48 pm
Location: mells , England, United Kingdom
Motorcycle: Honda Goldwing gl 1989

Re: Gas cap suction pressure and tank noise is not normal

Post by wingdings » Sat Feb 23, 2019 2:23 pm

hi saw your post try this then -

and also look at this too

and if you want to renew you petcock - I did post a how too on the site here - view topic - viewtopic.php?f=14&t=36257 hope this helps solve your problem :D :D :D :D :D :D

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BENJEE2112
Posts: 72
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Location: Port Charlotte, Florida
Motorcycle: 1995 1500i INTERSTATE
THE ONE STYLE "WITHOUT" REVERSE ((Danggit))

Re: Gas cap suction pressure and tank noise is not normal

Post by BENJEE2112 » Sat Feb 23, 2019 9:11 pm

Thanks for the input. Today I put the gas cap on (half way) to see what that would do. Bike ran like a top all day. But once again. When I got home. It was whistling away. even with it on half way. I opened it. Let it sit for a few minutes. Then put it back on (half way). started doing it again. I now have the cap soaking in SEAFOAM. I'll update the situation later. Thanks again. (AND EVERYTHING) lol. I had a girlfriend from Guin Alabama used to say that all the time..

kane67
Posts: 286
Joined: Tue Aug 18, 2015 2:15 pm
Location: Finland
Motorcycle: Honda GL1500-88

Re: Gas cap suction pressure and tank noise is not normal

Post by kane67 » Sun Feb 24, 2019 12:02 pm

Hi all,

How about -88 model cap? It does not have that red tube / breather nipple at all.
I always hear a pressure sound but never had any issue with it.
Gas smell was there when the heating isolation mat was torn down. Had also hard starting issues with hot engine after sitting an hour.

I placed a new heating mat under carbs, no issues since.
Anyways, there can be more than one reason. Just try to delete them all and your wing is perfect ;)

Br, kane

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wingdings
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Location: mells , England, United Kingdom
Motorcycle: Honda Goldwing gl 1989

Re: Gas cap suction pressure and tank noise is not normal

Post by wingdings » Sun Feb 24, 2019 2:04 pm

hi there !! I have a 89k wing - like yours it does not have the red tube either !! and you can hear the fuel pump starting up when you turn the ignition key on - my friend owns a 1998 wing on his it has the red tube on top of the fuel cap - you cannot even hear the fuel pump start up on his at all you just press the start button and it goes -on my 89k wing under the rubber matting there were lots of vac tubes I had to renew as the old ones were perished night mare to do ….

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BENJEE2112
Posts: 72
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Location: Port Charlotte, Florida
Motorcycle: 1995 1500i INTERSTATE
THE ONE STYLE "WITHOUT" REVERSE ((Danggit))

Re: Gas cap suction pressure and tank noise is not normal

Post by BENJEE2112 » Sun Feb 24, 2019 3:16 pm

I'm done with the gas cap seafoam soak. do I need to rinse the seafoam off with something or just blow it with the compressor and put it back on? I feel like such an idiot asking these easy questions. But I have screwed up so many things in my life. I figure it might help to ask first. lol. I was thinking break cleaner. But that might hurt the rubber gasket and ball inside.

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AZgl1800
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Location: Lake Oologah Indian Territory USA
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Re: Gas cap suction pressure and tank noise is not normal

Post by AZgl1800 » Sun Feb 24, 2019 4:44 pm

just leave it, it will evaporate...
blow it off if you want.
~John

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BENJEE2112
Posts: 72
Joined: Sun Sep 16, 2012 1:06 pm
Location: Port Charlotte, Florida
Motorcycle: 1995 1500i INTERSTATE
THE ONE STYLE "WITHOUT" REVERSE ((Danggit))

Re: Gas cap suction pressure and tank noise is not normal

Post by BENJEE2112 » Sun Feb 24, 2019 7:22 pm

THANKS John. that's what I did, Looks brand new. Have a good week



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