Gas dripping from tube under bike

[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 and had 3100 when I bought it last year. Bike is intact canister wise.

 

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! 

[Scud]

Under your tank there are two metal nipples, which may have hoses on them. One is a drain - to get water and excess gas away from the fuel door. The other is a vent, to allow air back into the tank to replace the gas as it is used. Since you heard a whoosh when you opened the fuel door, I suspect that you vent hose, or the nipple is clogged. I would first remove the vent hose and blow compressed air through it. If that fails you might need to clean the metal nipple under the tank.

 

Some people join the two hose from the two nipples. That seems like a bad idea to me. If they are joined (from a previous owner), try separating them.

[Scud]

David - I noticed you posted the same issue on WildGuzzi and have received some good suggestions there. I just thought of a quick test for you to see if the problem is with the canister.

1. Disconnect vacuum lines at cylinder head inlets and cover balance tubes with rubber caps.
2. Disconnect vent line from gas tank to canister - at the canister - so it functions like a passive vent tube (not connected to any engine vacuum). I think you might have to cut a single-use metal clamp to do this.

If your symptoms go away, then the canister is the cause. If not, then you have to remove the tank to figure out if something is clogged.

 

FWIW - I removed the canisters on both my bikes. I rationalized this from an environmental perspective by noting motorcycles are fully compliant with EU requirements without these canisters. I think were required only by California - so manufacturers in the US made 50-state compliant bikes, not 49-state and California-only variants. And here in CA, nobody even checks to see if the canisters are retained on the bikes.

[GuzziMoto]

In the USA the gas tank "vent" has a one way valve that only allows air to enter the tank, so that as fuel is used air can replace it so there is not a vacuum.

Common practice, at least to me, is to remove that one way valve. If you follow the line you should be able to see the valve. I believe euro bikes vent directly through the cap, but as I am not there I am not sure. 

[BMWDavid]

Scud, Sounds like a good plan. I'll try this. Yeah...I've posted here and on WG. Figured I'd get a nice balance of replies from members. Appreciate it!