BMW K bikes (Bricks)

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lhead71

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A while back when I first bought the bike, I posted about a stain on the bike's tank. After a few fill ups, I now see it is because gas is leaking down the side of the tank from the vent hole that is in the gas cap.

Why is that happening, any suggestions on how to fix it? It doesn't matter if I fill the tank full or half way.

    

charlie99

charlie99
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hmmmm sounds like someone has mis directed some of the breather tubes inside the tank lhead .....or the releif ports at the bottom of the tank are blocked ...thats pretty weird stuff huh ?

i think i have seen the correct way for connections in one of the schematics on the posts here some where ..

hey just a thought ....someone didnt put a piece of hose between the two bottom ports .......one is for the top vent hole ...the other is from the vent at the fuel pump which exits at the near same location under the tank ..they both usually are open ...and a little bowl is underneath to catch any stuff .

just a thought


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OGas leak onto tank out of the gas cap vent Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

lhead71

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I ran a wire through the vent tube and it was clear. I can't figure out why it continues to "weep" out onto the tank.

    

ReneZ

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There are two tubes running through the tank; one is for the drain of the tank cap recess through the hole at the left side of the cap, the other is a breather (the forward one IIRC). Both end underneath the tank right aft.
I'm wondering if you have a split fuel filter or similar that spays against the underside of the cap. Have you tried to run the bike with the cap open?


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Greetings from Florida! Having a 'new' K  :cyclops:    Surprised-o: 

Rene


BMW K100 - 1985 (0030029) Gas leak onto tank out of the gas cap vent Rain
BMW K1200GT - 2003 (ZK01223)
    

lhead71

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ReneZ I have run the bike with the gas cap open. The fuel filter is brand new. The one that seems to be leaking or weeping is the forward one that goes from the gas cap to under the tank. Both lines seem to be open. I pushed compressed air through the one in the gas cap to the bottom of the tank and it was clear. The other one I can't seem to find where it comes from.

    

ReneZ

ReneZ
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The other one is a breather line and ends just before the filler opening at the top of the tank. Have a look with the cap-unit removed and run the bike again (on the stand ;-) ). There must be something spraying against the filler cap arrangement for it to leak like that. If you've just fitted a new filter, are you sure you fitted it in the right direction? Otherwise it could partially block and create a higher pressure.


__________________________________________________
Greetings from Florida! Having a 'new' K  :cyclops:    Surprised-o: 

Rene


BMW K100 - 1985 (0030029) Gas leak onto tank out of the gas cap vent Rain
BMW K1200GT - 2003 (ZK01223)
    

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