Outboard fuel tank question

[Terence Pare]

The gas tank for my 6 hp Mercury outboard has a vent on the cap. I assume that the vent should be open when I am running the engine, but what about when I am not on the boat? Should I close the vent? I am thinking that by leaving the vent open, humid air finds its way into the tank and water condenses into the gas, causing engine problems.

Thanks

 

[Silvertip]

Re: Outboard fuel tank question

Closing the vent can also cause tremendous pressure build up which in severe cases can force fuel past the inlet needle and seat in the carb thus floodiing the engine with fuel. The best approach is to leave it open. If you do elect to close it, disconnect the fuel line from the engine.

 

[northwoodslivin]

Re: Outboard fuel tank question

Sorry to bump up an old thread, but I had this same question myself and was looking for an answer.


I have the same kind of tank, but the new 6 gal plastic ones, it has a thumb vent on the top of the cap. Question, when I am not using the boat I disconnect the tank and put the tank in the garage, but I leave the vent open just a hair so it can exhaust pressure. Or should I be closing the vent completely? Reason for my question is after reading a lot of the horrors that ethanol can do

Question is.. Will the tank ever explode and throw gas all over the place if the vent is closed and no lines connected to the tank, in a garage in storage while not in use?

 

[5150abf]

Re: Outboard fuel tank question

Why find out, just leave it vented it bit.

I am sure in Ontario you get some pretty good temp swings like we do here in Indiana, we can go from 40 to 70 in a day.

I have never shut my vent in 8 years and not had a problem.

 

[foodfisher]

Re: Outboard fuel tank question

Gas fumes are heavy and will crawl along the floor. Be sure no open flames or sparks are at floor level. Example: water heater, compressor motor