Vent on 3.5 gal gas tank

[Fred]

Is the vent on the gas tank suppose to be open or closed during motor operation. I've been closing it everytime I go out and releasing the pressure on the tank when my 235 is parked in its slip. I have a Mariner 8 hp with the forward and reverse on the throttle arm and it runs great. The 23.5 is very responsive under mariner power. Pictures of my boat are at the related link.

 

[Frank]

open while running

If you try to run it too long while it is closed the motor may stop. Close it while the motor is off to avoid water condensation from entering the tank.

 

[Tom Hultberg]

I leave mine open all the time and have

for years. Never had a moisture problem in the gas. Most moisture in gas comes from condensation in the tank. If you forget to open it your engine will start and run for awhile but a vacuume will form in the tank as the engine trys to draw fuel. After awhile, your engine will stop like it ran out of gas. It can be hard to start again until you get the vent opened. This happened once on a buudy's boat and when we really needed the engine, it went out on us...not fun. Leave it open, as it can also build preasure in the tank if there is no air escape for the expantion and contraction from heat. Remember, your car's fuel system has a vent...Toms/v Chrisanna II