Gas cap suction pressure and tank noise is not normal

Information and questions on GL1500 Goldwings (1988-2000)
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Posts: 8
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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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!


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