Is this normal? I disconnected the line from the charcoal canister to the catch tank. After disconnecting the line I unscrewed the gas tank cap and was greeted with the noise of escaping vapors. What gives?
edit: ah I just noticed that the gas tank uses a 2-way check valve, does that mean they only open after a certain pressure situation?

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Mine has been gone for years. I can't recall how I did the hoses though. If i had to guess I connected the hoses together minus the canister (mine got cracked during a differential mount replacement). Mine will give a good "whooosssssshhh" when I open the filler cap, especially on hot days near empty.

 

i had similar question...and i tried something new i think it seams to be working ... link to my thread https://www.rx7club.com/showthread.php?t=906282

 

The gas tank will still pressurize simply do to the return fuel. The canister is designed to take some of this pressure and feed it into the intake.

 

What I mean is, I took the line off to see if there is a problem with my evap system. Since I took the line off before the purge, the gas tank shouldn't be pressurized unless the check valves are pressure sensitive and will only vent to the charcoal canister once a certain amount of pressure has built up.