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Old 05-28-2009, 02:58 PM   #144
DolphinJohn's Avatar
Joined: Mar 2007
Location: Nature Coast, Florida
Oddometer: 3,949
Originally Posted by The Griz
I noticed this difference as well, and am a little stumped myself. The parts in question are #3 and #'s 18-24 in diagram below. On one hand, it makes sense that if the fuel pump is pumping fuel out then the tank would need to draw air in. Is that the spot though? But it would also make sense that it's a safety valve for the tank, in which any excess fual or gases would vent out there. The test would be to carfully check the valve (#21) to which way it flows.

I'm leaning more towards the mentality that things go out through there. This would make sense in the canister design as well, since the canister needs to get the excess gases fed to it from the tank. This seems like the spot. I think I'm just going to let mine dangle, given the BMW parts diagram calls #21 a "Ventilation Valve."

Ok, now I'm more confused. Isn't #5 the valve? I don't get why they show the hose broken up in to several parts. the hose from the top of the canister goes back, unbroken to the rear #5 then a short hose from #5 in to the tank.
The other hose from the top of the canister goes right across the bike to the "pressure switch" or whatever it's called. Another hose from that switch connects to a T which is one hose from each throttle body.

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