[BrianG]

It doesn't at all sound like an issue with the tank to me, but rather an issue with the fuel line. You said that the tank was pressurized and gas came out when you unhooked the line. That would tell me that the tank isn't the issue. Try moving it right next to the motor and see if it will run the motor. If it will, take a look at your fuel line. Maybe its plugged or too long for the size you are using. Could it be collapsing maybe? Those tanks work just fine for an outboard, and although they probably don't use fuel as quickly, the same principles apply. If it needed some sort of extra vent then it would need it for any application.