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-   -   Rubbermount_EFI Changed gas cap and experienced problems (http://xlforum.net/forums/showthread.php?t=2075943)

dayypete 21st February 2020 23:14

Changed gas cap and experienced problems
 
This is another problem I had with 2009 XL1200C sportster. I replaced the gas cap with one that was much easier to get on and off. The smooth flat stock gas cap is recessed in to the center metal piece and and PIA to take off. So I replaced it with one I purchased expecting there would be no problems.
Not to be.
Very shortly there were fuel issues where I would be running a speed and the bike would act like it was fuel starved. After a few turns at that, I went back to the stock gas cap and the problems disappeared.
This and problems with an LED head light and after market batteries I purchased have made me leery of buying anything non-OEM on these sportsters. Any ideas as to why the gas cap became problematic or gas caps others have used without problems to replace the stock gas cap?

Iron Mike 22nd February 2020 00:14

Blocking your tank vent???

Toejam503 22nd February 2020 00:22

Your new cap isn't vented. When installed it should turn and you should be able to get it to click, like the stock one.That tube that is in the fill hole is for overflow expansion and doesn't work well as a vent.

Iron Mike 22nd February 2020 00:26

I was unaware on how the new tanks vented, whether through the cap or the tube. Toejam's suggestion is viable. Somewhere you are not venting.

Toejam503 22nd February 2020 00:32

Hey Mike, you should see when you plug that tube for overflow, how the tank gets covered in fuel, on a hot day. I had a tank years back, that I had to plug the tube because it rusted thru at about half a tank (didn't want to replace it) and if you tried to fill it it would start pouring out of the overflow at about 1 gal full.

TUCCI 22nd February 2020 02:04

Cap might not be vented and its vapor locking. Compare it to the stock cap to figure out what's different.

Bored now 22nd February 2020 10:58

If fuel can go through the overflow tube then air can enter the tank through it surely, there is no one way valve in it? You may want to check your overflow is not blocked.

Folkie 22nd February 2020 11:24

Quote:

Originally Posted by Bored now (Post 5807524)
If fuel can go through the overflow tube then air can enter the tank through it surely, there is no one way valve in it?

No, there is a one way valve to stop that happening.

Bored now 22nd February 2020 12:34

Well there you go, leaned something new today.

SonWon 24th February 2020 19:56

2016 efi sportster, I bought a flush mount cap so I could use a tank bag. The new cap had a breather hole with no valving. I kept smelling gas and thought the new cap was leaking around the gasket. I finally figured out it was the vent hole and returned the cap. I ended up buying a new cap from HD (They have a one way vent.) and never had anymore problems.


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