Sounds like we need a decisive answer. You know somthing really positive on the tank having pressure would be to prevent crap from getting in there. 589659 brought up a good point, I wonder if its a sucking or blowing when you spun that cap? From the realm of carb flooding I would 'assume' its releasing pressure. A simple way to test would be to put a bag over the opening and see if it contracts or expands when you pop the cap.

DOA im very interested to hear what your mech says. Ask them if you are supposed to be able to blow through that line, I couldnt with my mouth, thus I assumed pressure was building, couldnt escape then flooding occurs. Im surprised these have been around since 01 and we are still guessing what the hell is going on here. [img]i/expressions/face-icon-small-smile.gif[/img] Iv owned mine 2 days now [img]i/expressions/face-icon-small-smile.gif[/img]

 

When you tried to blow thru the line, were you blowing into the tank or away from it???

 

Good call 589. In the engineers mind, I wonder if that was their mindset. That would definitely let air in the tank, but the check valve would not allow pressure to escape the tank. My 650 was buiding pressure in the tank cause when I took my fuel cap off one time, it popped right off the bike, there was that much pressure in the tank. Plainsman, I think your fuel filter in place of the stock system is the way to go. Damn!! Now I gotta go buy a new fuel cap and a $2 fuel filter cause I like your idea better!!

 

Away. I disconnected the T and blew toward the rear of the bike.

 

Well tinkering with pilots helped starting. Im at 3.5 rear and 3 front. Man does she run strong when its warmed up.

Here she is.

null

 

Just for curiousities sake, could you try blowing the other way thru the check valve??

Just wondering if my guess was on the right track.

 

I would but everythings all full of snow now and I dont want to get my lips in there [img]i/expressions/face-icon-small-smile.gif[/img]

If I tinker with it again Ill post, otherwise Im interested in hearing what DOAs dealer says mon.

 

Hey how much you willing to pay for a cap? I may end up with one [img]i/expressions/face-icon-small-smile.gif[/img]

 

just to put in my 2 cents the tank should never have pressure on it.
When the fuel is sucked out of the tank it puts the tank under a vacuum. thats why it is vented.
a vent wil most likely work in both directions to let air in and out depending on whether the tank is under vacuum or pressure the check valve is usually there so that fuel cannot escape.
this is how it works on most of my experiences which are mostly auto and truck related I don't personal know how the prairie is designed.

 

Honestlyinsane, that is what I am thinking too. The check valve is there to prevent fuel from running back down the breather tube and to let air into the tank so the electric fuel pump doesn't crush the tank like a beer can (like it would!!). However, that check valve also doesn't let pressure escape from the tank as it is---well---a check valve. This is all hypothetical mind you as I haven't ripped it all apart to test my theory. I'll play politicain and just say "that is the way it is and you will all obey my word as it is law"[img]i/expressions/face-icon-small-happy.gif[/img] Seriously though, I have no idea if that is what is actually happening, but that is what I'm thinking.