Fuel tank venting...fuel always exposed to the atmosphere

[tomc585]

So i've been thinking about the simple venting setup on my 1801. I dont like that the fuel is exposed (via the vent) to the open air in a water enviorment while docked and during the winter in my yard basicaly absorbing moisture. A shut off valve at the vent isnt a good idea (or is it?) because the tank needs to stabilize to keep from collapsing and expanding. I thought a vent with a check valve or an inline check valve that would work in both directions but stay closed when there was equal pressure. Tank filling could be compromised but a bypass could solve that.
I looked but I cant find anything on the market.
Is this a bad idea?
I dont want an evaporative system.

Thoughts?

 

[Navigator]

You want to crack a tank install shutoff valves. The flexing from the expansion and contraction will soon crack a weld especially with a marine size tank. I guess if you really wanted to you could hook up your vent to a small partilly empty fuel bladder and purge it with an inert gas but the effort?. Most people simply use fuel stabilizer which should easily get you through winter. I've been know to empty my boat gas at the end of the season into my car over a month or two...kills two birds with one stone.

 

[Puck-n-Fish]

expansion and contraction will soon crack a weld

Yes it will...these tanks are not welded on the inside, so a crevice exists on the backside of the external corner welds(inside the tank). This is a great spot to start a fatigue crack. I think the risk of something going wrong is not worth the benefit. Also, your not going to find a check valve that would "work in both directions"...