View Full Version : Atmospheric Pressure hose

02-02-2014, 08:50 PM
Quick question that I could not find an answer to...
Previous owner removed the carbon canister but didn't get rid of the excess lengths of hose being routed to the rear cowl, so I accomplished that task today. In the mix of it, I checked the one way valve for the pressure vent hose, and sure enough, it was on backwards. I read some posts that claim you should just remove it and run the hose directly from the bottom of the tank to the ground. So I did.

I lifted my tank to check the air filter and throttle body balancing (if you don't have a Morgan Carbtune, get one), and gas was spewing out of the pressure vent hose. I know this is probably the purpose of the inline one way valve, but wouldn't there be a similar check valve built into the gas cap or do I have a faulty gas cap? I could understand if it was making its way past the gas cap seal and draining out of the overflow hose, but its not the case.

02-03-2014, 12:51 AM
Is your gas cap seal itself leaking? Known issue, btw. There are a few threads on here on how to put a Viton (I believe) O-ring under the seal to help lift it up a bit and seal better. You can also cut a ring out of a pop can and do the same thing.

02-03-2014, 06:40 AM
Its not the cap seal, it's free flowing from the pressure vent hole on the underside of the gas cap (inside the tank) and all over me foot. Also, after every ride there will be a small bit of fuel on the ground within an hour of stopping it. There is only a half tank right now, I don't know how its reaching the top of the tank to flow out that vent. Maybe I have to stop riding it like a raped ape.