Gas dripping from my '03 V11 LeMans

[BMWDavid]

My '03 V11 LeMans that I've owned for a year just did something strange. Parked it in the garage after a 40 mile ride and a few minutes later there was a puddle of gas under the bike. It appears to be coming from a larger diameter hose positioned near bottom of trans.

 

It has never done this before. Bike has 4500 miles on it now and had 3100 when I bought it last year. Bike is intact and 100% stock.

 

I noticed when I opened the gas cap I heard a whoosh sound. Never had that before. Left cap open all night and no further dripping. Closed cap today on a cold bike and it then dripped a few drops from tube.

 

So...what is going on?

 

Thanks!

[JoeW]

Obviously the tank is building pressure. These bikes are supposed to vent through the carbon canister. There is a check valve in the vent line that may be stuck. Low mileage bike does a lot of sitting. On my 2000 V11 Sport I removed the rubber diaphragm in the gas cap and allowed the tank to vent through it.

[fatbob]

A lot of folks remove the canister altogether. I did, but there are no DMV inspections where I live. Your carbon canister could be full of fuel thus no venting.

[fotoguzzi]

I'd get rid of the canister's and plug the ports on the intake manifolds..
 also there is a tank tip over valve that needs to be vertical to work.. sometimes the factory put them in backwards so they didn't vent proper.. since you never had this before it's unlikely but worth checking.
if it was hot the expanding gas in a full tank needs somewhere to go, out the vent tube it goes.. happens mostly when parked in the hot sun, not your case..

Nice bike, don't panic.. you can resolve this..

[rocker59]

Check valve in the vent line is stuck.

[BMWDavid]

I guess I'll be pulling the gas tank off. Going to try and run the tank down a bit by riding it so its a little easier to remove. Not sure I understand why a stuck check valve would cause gas to drip from tube. Trying to visualize the path gas would take to end up dripping from hose.

 

[rocker59]

I guess I'll be pulling the gas tank off. Going to try and run the tank down a bit by riding it so its a little easier to remove. Not sure I understand why a stuck check valve would cause gas to drip from tube. Trying to visualize the path gas would take to end up dripping from hose.

Is the tank near full?  Was the engine hot when you parked the bike?

If yes, and the ball valve is stuck open, then expanding fuel can run out the hose.

I see this a lot in the summertime with guys who will pull into a gas station and fuel up, then hang around for a few minutes taking a break.  Invariably, the bike will puke some gasoline on the ground under the bike via the overflow tube.  If they took thier break first, then fueled before leaving, that wouldn't happen.

We're just offering theories here.  You'll have to figure it out by looking, but I say near full tank with hot engine parked in garage, fuel expanded and puked out the overflow line...

[BMWDavid]

Is the tank near full?  Was the engine hot when you parked the bike?

If yes, and the ball valve is stuck open, then expanding fuel can run out the hose.

I see this a lot in the summertime with guys who will pull into a gas station and fuel up, then hang around for a few minutes taking a break.  Invariably, the bike will puke some gasoline on the ground under the bike via the overflow tube.  If they took thier break first, then fueled before leaving, that wouldn't happen.

We're just offering theories here.  You'll have to figure it out by looking, but I say near full tank with hot engine parked in garage, fuel expanded and puked out the overflow line...

Yep...tank was almost full (about 20 miles/half gallon down) and I parked it in my garage after a good run. Ambient temp was in the 70's. It has never done this before under similar conditions and even much hotter situations. When I opened the gas cap the whoosh occurred. The gas level was done an inch or so...not even close to expanding up into the overflow hole under the gas cap well.

The puking stopped as long as cap was left opened. Even an hour later when engine had cooled significantly it would puke a bit after cap was closed. So I left cap open all night.

The next day on a cold bike I closed the cap and even then about an hour later there was a few drops under the bike...as if the vapor pressure in the tank was enough to cause dripping.

[rocker59]

Keep in mind that the small drain hole on the rim, under the cap is a water drain.  It's not the vent.

[BMWDavid]

Keep in mind that the small drain hole on the rim, under the cap is a water drain.  It's not the vent.

Ah...of course. Forgotten that. So, the gas is flowing out from what location within the tank?

[Scud]

David - I noticed you posted the same issue on V11LeMans.com.  I replied there.

http://www.v11lemans.com/forums/index.php?showtopic=19428

I'm sure you'll get this sorted quickly.