1100 - tank overflow when not full...

[Jamieboy]

Each year I go for a trip with my mate who has an 1100 GS (I've an 1150) - I'm always annoyed by an issue with his bike which he inexplicably seems content to ignore...

Fuel pisses out of the overflow pipe when it is stopped when the tank is at anything over about 1/2 full. This basically means he's unable to fill it up unless riding off immediately. It happens when on both side and center stands but seems worse on side stand.

It is especially bad on ferries when the fuel has been sloshed around by the movement of the boat - quite embarrassing when the whole vehicle deck stinks of fuel, and also probably somewhat hazardous.

I'm thinking it is probably old fuel lines/seals in the tank having perished - however I have never looked inside a tank so don't really know what I'm on about.

Anyone had this issue?

 

[fatnfast]

Sounds like an internal split/detached in the breather/over flow pipes. As you point out these go thru the tank. I would look at the overflow pipe that starts at the fuel filler first. Blow down the pipe whilst covering the small hole inside the filler cap. It should be sealed, so no escaping air. Watch out for a mouth full of fuel though and dont use an airline. Not a huge job to replace. Bit dumb of him to ignore, it certainly wont get better but could get worse.

 

[MattW]

My 1100 used to do just that.
As above, it was a perished breather hose inside the tank. Pretty simple to replace once the tank drained and off. I replaced all the hoses and the fuel filter while I was in there (except the stupidly expensive little U shaped hose). If he does it, make sure he uses the correct grade of submersible fuel injection hose for the high pressure stuff.

Edit: I've seen someone be denied boarding on a ferry because of a fuel leak...

 

[fatnfast]

And make sure he buys in tank fuel hose to replace them such as this:
https://www.merlinmotorsport.co.uk/p/rubber-in-tank-fuel-hose-by-cohline-per-metre-2190-0615

 

[Bendy toy]

Don't use silicone hose for fuel lines. It's tough as boots handles 250 degs C acids proof you name it. But petrol makes it go all soggy in just a few days.
DAMHIK.