990 SD fuel vent leak/drip solved

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sam46
Two wheeled terror
 
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Location: wales - uk

990 SD fuel vent leak/drip solved

Postby sam46 » Tue May 22, 2018 8:26 am

Hi all, i recently had a fuel drip on the duke after a spirited ride on a nice warm day. I search through lots of forums and advise which ranged from simply removing the rubber nipple underneath the fuel cap to completely removing the fuel cap rubber gasket. After trying both of these solutions i wasnt happy with either as i still had fuel leaking, but not quite as bad.
What i discovered after further investigating is that number one its just a few easily accessible bolts to completely remove the fuel cap, thus avoiding dropping any small parts in your tank.
Image

And two, after removing just 3 small bolts holding the gas cap together you reveal the rubber gasket seal.
Image

Now after 11 years of venting petrol fumes and varying temperatures this rubber gasket does get quite a lot of deposits and drys the surface out. There are two split nipple type vents on this gasket which should open when pressure build acting as a one way valve. On mine the deposits had pretty much fused them closed, stopping them venting and forcing fuel out of the drain vent giving the fuel drip/Leak.
Image


Simple clean with wd40 to clean off residue and soften up the rubber, and these vents function as they should and cure the leak.
Image


One thing to be cautious of is that to replace the the round ally plate that the springs sit on is put back with grooves facing the springs. If you dont you cant shut your fuel cap...
This is how it should be:
Image


Hope this help :)
07 SD 990 - Akros - Awaiting major mods
05 SD 990 - RamAir pods - Akro Ti - Sold
07 SD 990 - Superduke heaven RIP
KTM 250SXF, KTM 300EXC, KTM 450SMR, CRF450, KTM 250XCF, YZF R1 09, YZF R1 03, YZF R6 02, YZF R1 98

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Aphex
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Re: 990 SD fuel vent leak/drip solved

Postby Aphex » Tue May 22, 2018 2:28 pm

Nice write up.

I've always just blasted the vent holes with compressed air, might had to pop my cap off and see if it's the same issue.
08 SD, Mivv Suono, Rottweiler airbox. Current map: One some guy sent me from the internet.

Me so Hoony.

Varinn
Minimoto racer
 
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Re: 990 SD fuel vent leak/drip solved

Postby Varinn » Tue May 22, 2018 8:39 pm

This is a good find but might not be a cure for all of us, my entire gas cap/lock assembly was replaced a year or two back after my original lockset failed, I've had the same problem since the same time despite having checked all my other vent lines etc.

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sam46
Two wheeled terror
 
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Joined: Fri May 17, 2013 4:16 pm
Location: wales - uk

Re: 990 SD fuel vent leak/drip solved

Postby sam46 » Wed May 23, 2018 7:09 am

Varinn wrote:This is a good find but might not be a cure for all of us, my entire gas cap/lock assembly was replaced a year or two back after my original lockset failed, I've had the same problem since the same time despite having checked all my other vent lines etc.


Sounds like you've got the fuel leak "dribble" issue not drip issue mate :lol:
07 SD 990 - Akros - Awaiting major mods
05 SD 990 - RamAir pods - Akro Ti - Sold
07 SD 990 - Superduke heaven RIP
KTM 250SXF, KTM 300EXC, KTM 450SMR, CRF450, KTM 250XCF, YZF R1 09, YZF R1 03, YZF R6 02, YZF R1 98


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