Fuel spilling out tank breather

On my 09 WR450 when riding hard on rough terain I am loosing a ton of gas out the the breather tube (the one coming from the gas cap) It leakes even when the tank is only half full. I have replaced the one way valve and no change. The valve is in correctly.

Anything else I should look at before I run out of gas in the middle of nowhere:foul:

You sure it's not leaking from the gas cap :bonk:

You sure it's not leaking from the gas cap :bonk:

No, its for sure from the breather hose. It runs down the back of the front fender.......

No, its for sure from the breather hose. It runs down the back of the front fender.......

I don't know what to say. Even without a valve you shouldn't get much gas coming out and with a valve should be none.

Have you tried filling the tank and laying the bike on it's side to diagnose more???

I had the same issue on my 2009 wr450. I removed the stock plastic breather valve and just run a hose and problem solved. I even tried several of those billet aftermarket breather valves and they all leaked as well. Can't for the life of me understand why a regular piece of hose with no valve would not leak, but it doesn't.

I don't know what to say. Even without a valve you shouldn't get much gas coming out and with a valve should be none.

Have you tried filling the tank and laying the bike on it's side to diagnose more???

had one bike that gas cap itself failed and did the exact same thing.. it would run fuel out the vent hose no matter how much was in the tank. I took the cap apart and gutted it, saw nothing wrong with it, and it still did it..

a new cap took care of it.. it was not near as new a bike as you have, but same problem..

thanks, ill try the hose first, then a new cap.

The gas vapor in the tank expands dramatically as it warms up. Could be something weird with the construction of the gas cap allowing it to push gas out and overwhelm the one way valve, as it sloshes around in rough terrain.

The one way valve is really only for tip-overs. Just a hose should be fine if you keep it rubber side down.

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