Water in Fuel

[carry-on]

 Recent problems with water in my fuel pump and carb. I have a 2010 4hp Nissan with remote tank. I use non-ethanol gas.
The remote tank stays in the boat and I keep the air vent cracked because the pressure build up in Florida heat is significant. Don't know the source of water, maybe our heavy rains put some water in the tank through the air vent.
The screen filter at the bottom of the gas pick up line is lodged against the bottom of the tank. This is effective in keeping the screen filter in place but puts the intake where any water would be. Should I raise the intake an inch or more to avoid water? I don't plan to use the bottom inch of gas anyway.
To remove the pick up leg, if I shorten the leg, seems I need to remove the built in threaded gasket at the top or pull the screen filter off and fish it out of the tank, a fun game. Can I get a replacement threaded gasket if I damage the original?
Thanks.

[brackish]

I'll offer my advice knowing I will draw alternative opinions.  Close the vent when not in use, the tank is made to handle the pressure.  Do not run your motor dry.  Do not disconnect the fuel line from the motor and only from the tank when you need to fill it off the boat.  Give your bulb a squeeze AFTER you shut your motor down before you leave it.  Top your tank off frequently keeping it as full as practical.  The theory is if your fuel system components see a lot of temperature changes with a lot of open surface where humid air can get in, the water in the air condenses on any fuel void surfaces during the cooler overnight hours and collects over time.

[MacGyver]

what could work with no modification is to tilt the tank so that the pickup is above the bottom part of the tank, that way the water would settle to the lowest part and not get picked up into the engine.
then what you could do, is dump the fuel every couple months, or also could run the fuel through a water separator filter to extend the use of the fuel. that kind of filter can be purchased as a funnel as well, so you could pour the fuel through the funnel into a gas can, then back into your tank for use.

Ethanol added fuel is hydroscopic, so the water could be being sucked out of the air into it as well.......

Mac

[Salty19]

Yep, brackish is right.  You're drawing in warm humid air and it's condensing on the cold fuel.  Builds up over time especially if you don't burn through much gas.

Keep some air space at the top of the tank and the vent lid shut.

[skip1930]

Source of water [if not pouring in from rains] is probably from CONDENSATION. Especially in Florida.

Side Bar: For every 1,000,000 btu's burned produces 100 lb of water vapor. Since water won't burn we see the water that drips out of the automotive tail pipes. This just goes to indicate water is all around us. And it makes Down-South a miserable place to live [my opinion].

Anyway, the gasoline floats above water, so find an gas tank where the entrance of the pick-up tube is an inch or so above the bottom the small tank. Ethanol to the tune of 10%, which you say you don't use, will absorb a tiny bit of water but that's like peeing into the ocean to make it overflow. Ain't gonna to happen.

At our county aeroport we stick a long hard plastic PVC tube down in our 3,500 gallon in-ground diesel, gas and av-gas tanks and use a positive displacement gear driven hand pump and suck out the bottom foot or so of fuels-water mix on a regular basis. [we burn off the smag that we collect]. This is in addition to fuel-water separators used on all pumps plus an exciter-dryer chemical for our Net Jets. Just not possible to get away from water vapor.    

Sunshine and heat~ On the hottest day I'd pop the vent and let the pressure out. Then seal it up. Sure the plastic tank [?] will suck in during the cooler evening. So what? That may prevent the formation of condensate. Just like in people breathing makes water.

skip.