Leaking gasoline

[Barquito]

I keep my gas for my outboard in the back of the cockpit. I have been having a problem with the gas oozing out of the can when it gets hot in the summer. The air the tank expands, and forces the gas up the tube. If the tank were perfectly sealed the gas would stay put, however, it is not and some comes out. I am worried if I leave the vent open the gas will get wet on our (very) humid mornings. Should I get a tank that is sealed better, or am I missing something.

[Freesail99]

Don't fill the tank with as much gas.

[sailingdog]

The tank should be vented if it is that full. You should leave about 5-10% of the tank empty to accommodate expansion, as both air and gasoline expand as they heat.

[Omatako]

Originally Posted by Barquito

I am worried if I leave the vent open the gas will get wet on our (very) humid mornings.

It'll take some serious dew to enter the vent, I reckon in anything other than a full submersion there will be no water getting into the tank.

Leaving some air in the tank means that when it does vent it bleeds vapour and not liquid fuel. Both are dangerous when exposed to a naked flame but the vapour will dissapate long before the liquid. Still it's a REAL good idea is not to take a naked flame into that area.

But, definitely, the tank must vent. FWIW another down side to not venting is when connecting to the outboard, the pressure transferred up the pipe is often enough to force excessive fuel past the needle and seat in the carb, flooding the motor and making it really hard to get started.

Andre

[sailingdog]

If the tank is fairly full, the condensation should be minimal, even with the vent open. And having the gas get wet is better than having the boat blow up IMHO. The amount of gasoline fumes that will come out of the vent is far less than is created by spilling even a small amount of liquid gasoline.

[hellosailor]

AFAIK real gasoline tanks always have a vent, but that vent is supposed to be opened DURING use and SECURED when not in use. If you do not secure the vent, you will have a gasoline odor and the chance of a spill. Leaving some air space in the tank, to allow for expansion, is a good idea since otherwise the full tank could push at its seams and potentially rupture.

But when a tank is not in use? No way I'd leave the vents unsecured!

If there is a problem with the tank forcing pressure up the fuel line, that's pretty easy too. Disconnect the fuel line, that fitting should also self-seal or have a shut-off valve to use when there's no fuel line connected to it. If it doesn't find a way to cap it off, because leaving fuel in the carb will cause gum to form in the carb. With a gasoline engine that "sits" for long periods without use, you are always better off shutting off the fuel supply and allowing the engine to run itself dry--preventing the fuel in it from gumming it.

[sailhog]

Barquito,
Add an appropriate amount of fuel stabilizer to your fuel, and only fill the tank 95% to capacity, as Sailingdog recommends. The fuel stabilizer should be able to handle the condensation, and also keep the ethanol in the gas from degrading (it only lasts 2 months without stabilizer, and a year with it).

[Barquito]

Thank you all for your responses. I never thought about where else the fuel might be going (other than into my cockpit!). My motor does start hard, possibly because it is flooded from that extra fuel pressure. I'll just keep the vent cracked while I'm away and "breathe" easier.