Originally Posted by JimN
If the sound occurs and the smell of gas in really strong immediately after, it's positive pressure. If it was suction, it wouldn't be so strong. With a pressurized tank, you could easily feel the air rushing out.
I agree the smell test may be valid, but easily feeling the air escape around the cap is harder to be certain of...
I've exhaustively researched the perko fill/vent systems today.. Even called perko although they were closed. They are open until 4:20. What's up with that? Smoke break? Anyway, Seems they call it a 'fill/vent' system only because the vent tube, which allows for more rapid filling, is contained in the unit, but behind the sealed cap that is sealed with an o-ring I might add. They also sell 'fill' systems that expect the vent to be a through hull fitting elsewhere. With the 'fill/vent' system, it seems it really is a closed system. It's hard to imagine the cap is designed to vent, and if it is, where? Again I'm not at my boat, but I believe all the holes in the cap are blind and only there to allow the cap tool to have a place to grab the cap. And if the cap were indeed 'vented', funny they'd add an o-ring to seal the circumference...
Bigmac, you've pointed out that you have the same vill/vent perko inlet. I realize you have one and not two orange hoses as I do, but have you found a vent on your boat that doesn't lead to the area just BEHIND your sealed fuel cap? Because that really isn't vented if the cap is tight and sealed..
I cannot believe they'd design the system without a provision to at least allow air to be drawn in somwhere. And at the same time cannot find such a location on my boat where air could be drawn in, unless it's something on top of the fuel pump cartridge itself..
I'm not having any problems with my 'ventless' system as far as driving goes..
But if something is plugged or malfunctioning, I'd like to know and fix it..
thanks for helping me track this down guys..