Fuel....whats going on?

[Sea Shift]

I was changing my fuel water separator today and like the good home mechanic i dumped the contents into a jar to check for water/crud. Didnt see any separation of water but did see this? Any ideas? Fuel just evaporating and condencing back into the jar? Keep an eye on the condensing drops as they hit the surface. You can see then drop half way down the jar.

 

[Hookup1]

looks like fuel floating on water. Teaspoon some off of top and bottom. Carefully see which one burns.

You have been fighting water in fuel for a long time. What's changed to make the problem go away?

 

[DennisG01]

I can't really see anything happening once the drops hit the surface... but if they're dropping down, then they might be water. Humidity in the air?

How long did you let the jar set? If only a short time, give it at least an hour (without moving it) and then look for noticeable separation

 

[Sea Shift]

You have been fighting water in fuel for a long time. What's changed to make the problem go away?

Whats changed? I replaced the fuel tanks that had 1/4" holes in the top!!! Amazing how much that helps. I'm not having water problems now that i know of. Just havnt seen fuel react this way before when changing the fuel water separators and found it interesting. I let it set and was seeing this. It could well be that on a warmer day when exposed to hair the water in the air is actually condensing into the fuel?

 

[Hookup1]

Whats changed? I replaced the fuel tanks that had 1/4" holes in the top!!! Amazing how much that helps. I'm not having water problems now that i know of. Just havnt seen fuel react this way before when changing the fuel water separators and found it interesting. I let it set and was seeing this. It could well be that on a warmer day when exposed to hair the water in the air is actually condensing into the fuel?

Is your boat in the water and you have run it this season? Or is a pre-launch check of the fuel filter?
Single engine single filter or twin engine two filters?
Which tank did the fuel come out of? The new tank or the old tank?
Where the o-rings on the fuel fills replaced?
What type of fuel? With ethanol or without?
Stabilizer added last fall when boat was put away?

When you pour the contents of the fuel filter can into a container some of the water will suspend in the fuel. It will separate out quickly at first then gradually.

"It could well be that on a warmer day when exposed to air the water in the air is actually condensing into the fuel?" - Nope...not buying that.

 

[Sea Shift]

Is your boat in the water and you have run it this season? Or is a pre-launch check of the fuel filter?
Single engine single filter or twin engine two filters?
Which tank did the fuel come out of? The new tank or the old tank?
Where the o-rings on the fuel fills replaced?
What type of fuel? With ethanol or without?
Stabilizer added last fall when boat was put away?

When you pour the contents of the fuel filter can into a container some of the water will suspend in the fuel. It will separate out quickly at first then gradually.

"It could well be that on a warmer day when exposed to air the water in the air is actually condensing into the fuel?" - Nope...not buying that.

I do keep the boat in a slip but use it on a weekly or bi-weekly basis. It has dual engines and both tanks were replaced 2 years ago. All fills replaced too. As for our fuel yeah im in CA so we have Ethanol so that sucks. We dont really "put away" Here since i crab in the winder and there is always something going on. This is just part of maintenance and thought it was interesting.

 

[Hookup1]

I do keep the boat in a slip but use it on a weekly or bi-weekly basis. It has dual engines and both tanks were replaced 2 years ago. All fills replaced too. As for our fuel yeah im in CA so we have Ethanol so that sucks. We don't really "put away" Here since i crab in the winder and there is always something going on. This is just part of maintenance and thought it was interesting.

You did all the right things. I fought water in fuel problems for a number of years. Particularly early in the year when I too my boat South to Florida. I tried stabilizers. switched to running only ethanol-free fuel, installed O-rings on fuel fills (mine were non-existent). A few times I thought the stabilizer caused the water to appear. Got to the point where I went to Siera clear bowl fuel filters in place of the Yamah cans.

My "normal" start of Winter boating is to dump the fuel out of the filters, fill with new fuel, put them back up and run the boat (bouncy ride trying to get any water in suspension). Repeat later or next day. I was never able to pump the water out. This was the only way I found to clean the fuel up. It's a pain for my first few days in FL but my problem would go away.

I don't know where my water was coming from. I suspect fuel fill O-rings and phase separation when using ethanol fuel. It doesn't take much water to cause phase separation after which the 10% E10 ethanol and the 0.5% water will drop out of the fuel.

Good luck!

BoatUS: Phase separation occurs when ethanol in fuel absorbs water from the air, forming a second layer of ethanol–water sludge at the bottom of the tank. This happens because ethanol is hygroscopic — it attracts and holds water — and can dissolve up to about 0.5% water by volume before the two phases separate mobilemarina.co+1. In a 20‑gallon tank, that’s roughly 12 ounces of water. Marine environments, with high humidity and frequent temperature changes, accelerate this process