Venting a an Outboard Gas Tank

[ruddneck]

This is probably a stupid question, but I'm compelled to ask.

Should I store my outboard gas tank with its vent closed or open?

I have 25-hp Merc outboard for my aluminum boat with the detachable plastic 6-gal gas tank. I store the boat outdoors (but covered) in my driveway and leave the gas tank vent open. I do so chiefly for safety--I left the vent closed overnight once in the heat and the tank ballooned up with fumes. But I wonder whether even though I have the tank full and add Stab-il to the gas, is the fuel absorbing water from the air and getting foul because the vent is open?

Thanks!

[bigmouth]

yes

[Bob H.]

Store tank with vent closed but not underneath a cover that doesn't allow airflow, also don't store in direct sunlight. Sunlight will eventually degrade the plastic tank. If the vent is left open moisture will get in. Use a stabilizer if you don't plan on using it for more than a month.