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What Happened?


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On my way back from Klamath Falls today I stopped in Susanville to refill the bikes tank then my tank...with the bike upright I filled up the tank too much and fuel would have dribbled over the tank if I just closed the lid so I leaned the bike from side to side and it all went in. Didn't think anything more to it and proceeded onto Burger King for an over-calorie lunch. When I came out I noticed a puddle of fuel below the bike, coming out of a tube. Again, didn't think much of it...maybe its the overflow tube as I thought I might have put too much in. Headed out of town when the bike stalled then went into a bucking fit after restarting. Pulled off the side, got off, looked about, still dribbling fuel out the little tube, turned around and struggled with her back through town looking for a bike shop...any bike shop. After going back and forth for about 15 min...no shop...she seemed to be running smoother so I headed back out of town and after another 10 minutes she was singing as sweetly as ever. Made it home after another 200 mi, as if nothing happened.


What happened? :S

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You temporarily flooded your carbon canister keeping the tank from venting. The rough running was caused by pulling a vacuum in the fuel tank and thus spoiling the effectiveness of your fuel pump.


Running the thing for a bit allowed the canister to purge so things went back to normal.


Keep an eye on your fuel gauge and how it works for awhile. If the vacuum condition got severe enough, you may have collapsed the tube and blocked clear motion of the fuel level sensor.

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As you found out, not a good idea to let a full(to the brim) tank sit for any period of time as the fuel will expand when it heats up.

Best to gas & go.


Eat first/gas last.

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If you overfilled the canister enough to get that much fuel out of the vent, you can count on the charcoal starting to deteriorate. Eventually, the fines from the disintegrating charcoal will begin to accumulate and block the hoses from the canister. The canister needs to be replaced or, as I have done with my last 7-8 BMWs, and those of several friends, it needs to be simply removed, the tank vent hose rerouted, and the lines to the throttle bodies capped (this process is often referred to as a "canisterectomy"). This is the way the bikes are delivered in non-US markets (i.e., not equipped with a canister in the first place). Once the canister is gone, you'll never have to worry about this issue happening again.


fn: While the plastic tanks on the K12LTs were famous for collapsing from vacuum in a way that damaged the fuel level tubes at ~1/4 full, the R1150GS tanks are steel -- if they collapse, you'll know it, because they don't "bounce back" when the vacuum is relieved.

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