How long for water to separate out of gas?

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Seaman
Joined
Aug 15, 2007
Messages
62
So I've been having some issues with intermittent bogging when cruising ('90 Merc. 4.3L). I'm pretty sure that it's an issue with water in the fuel. I've installed a fuel/water separator filter and am now going to siphon the remaining gas out of the fuel tank. I read that you can let the gas & water separate and then reuse the gas. My question is how long do you need to let the gas to sit to make sure that the gas & water have completely separated out? Does it take place pretty much instantly or do I need to let it sit for a while? If I need to let it sit, how long would you recommend?
 

stonyloam

Vice Admiral
Joined
Mar 13, 2009
Messages
5,827
Re: How long for water to separate out of gas?

Overnight should do it. How much gas are we talking about? You should be able to take a sample from the bottom of the container and put in a glass jar and see the water on the bottom.
 
Joined
Mar 27, 2010
Messages
3,008
Re: How long for water to separate out of gas?

yeah use a clear container so you can look thru it. If there is water in the tank it will be at the bottom, and should be drawn out first.
 

superbenk

Commander
Joined
Oct 27, 2008
Messages
2,022
Re: How long for water to separate out of gas?

Is your water/fuel separated a bowl type you can drain? If so, check the bowl, if not replace the one you have & dump the gas out of the old one into a glass jar. Let it sit overnight.
 

ENSIGN

Lieutenant Junior Grade
Joined
Jun 21, 2009
Messages
1,179
Re: How long for water to separate out of gas?

Put some red food coloring in the gas,it will only mix with the water which will be at the bottom of your container.
 

Grub54891

Vice Admiral
Joined
Jun 17, 2012
Messages
5,928
Re: How long for water to separate out of gas?

I've set the container outside in the winter,let the water freeze, dump off the fuel.Then add some sea foam just for insurance.You can freeze it in a freezer but don't let the wife catch ya!!
 
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