moisture in fuel

[67hat34c]

It would appear that that majority of the water that gets in the fuel tanks comes from the vent. I wonder if a dryer in the vent line would work. Use a dryer from an air compressor. if this works then it could possibly help keep fuel tanks dry, mainly the gasoline tanks subject to ethanol fuel. this could possibly help keep the stuff from forced phase separation.

[Genesis]

The majority of water that gets in the fuel comes down the fill pipe due to worn O-rings. The vent, properly-designed (and it is on Hatts) should not contribute anything material to the problem.

[67hat34c]

Sounds right, however warm moist air being sucked in should condense when cooled right? that is what i ment instead of sea water. due to ethanol in the gas would the ethanol attract the moisture and absorb it. tank has alot of surface area.

[34Hatt]

Steve
Your are right when it gets sucked in that is why up here they are saying not to keep it filled all the time. Basically put in what you will use in the next week or two. Then for winter time ( something a lot of you don't know about ) keep it empty and tape up the vent, also if you don't cover the boat cover the fill cap with white tape. The sun hitting the chrome or stainless every morning makes that sweet and drips down the hose into the tank. You can manage to get by once you change your tanks.

[Genesis]

Condensation is a non-starter guys. I've run the calculations on this and over a YEAR's time the maximum amount of water you would condense in a 300 gallon tank, assuming that you had daytime temperatures in the 60s and nighttime temperatures in the 30s with the possible humidity swings (remember, once you hit condensing numbers its all as you no longer have water in the AIR) is about a tablespoon's worth. This assumes the tank is nearly EMPTY!

If you're getting water in your tank its not getting there from condensation.

[WishFull Thinking]

I'm convinced most water in fuel tanks comes from the fillers. I look after 10 boats, and two of them are set up with fillers that actually come up off the deck and have pipe caps on them and they have no water in the racors EVER. The other boats have the standard flush filler with the o-ring and they all had periodic water problems. I have replaced the O-rings (some were missing entirely) and we'll see what happens.

[MikeP]

I also keep the filler cap threads well greased with a good thick marine grease. This does two things - keeps the caps from seizing and adds a little bit of sealing capability.