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Author Topic:   Water in Fuel Tank
David Jenkins posted 09-21-2015 09:04 AM ET (US)   Profile for David Jenkins   Send Email to David Jenkins  
My 1974 Outrage 19 has [about a] 40-gallon aluminum tank in the hull that is vented by a hose that runs under the deck for about three feet before coming above deck and connecting to a vent hole topside. Where this hose runs below deck, it became compromised, and consequently water got into the boat's fuel tank. I have siphoned the fuel into a 42-gallon Pate tank that is now resting on cinder blocks next to the boat trailer. Looking at the fuel in the Pate tank, it appears to be about 15-percent water. The 42-gallon Pate tank is almost completely full of this fuel-water mixture. It appears that the fuel and water are clearly separated, with the fuel on top.

I am thinking about carefully siphoning the good gasoline out of the Pate tank into 6-gallon containers and then putting the good gasoline into my automobile. When I get close to the layer of water I will stop and properly dispose of the remaining fuel-water combination. Does anyone see a problem with that?

Even though this fuel is 10-percent ethanol, my thought was that the fiberglass Pate tank would not have contaminated it (and it would not have hurt the Pate tank) since the ethanol fuel has been in the Pate tank for less than 24 hours. Right?

Does anyone have thoughts about these two questions?

Thank you!


jimh posted 09-21-2015 09:46 AM ET (US)     Profile for jimh  Send Email to jimh     
If the gasoline fuel in the tank was a mixture of gasoline and ethanol in a 9:1 ratio, and if there has been a phase separation of water and gasoline, I would have concern about the gasoline. It is my understanding--as I don't have any first hand experience nor have I taken any measurements of my own to go by--that ethanol-gasoline fuel which is mixed with water, and with so much water that the water cannot be absorbed into the fuel but rather separates out, will have lost the ethanol portion of the fuel into the water. That is, you now have two mixtures: one of gasoline without any ethanol, and one of water and ethanol.

The problem with the gasoline that remains is its octane rating. The ethanol was an octane booster for the gasoline, and, without any ethanol left in the gasoline mixture, the octane of the gasoline will be below the normal level.

If you really want to make use of the gasoline you take off the top phase from the separated tank, you probably should mix it in small quantities with fresh gasoline, and probably with fresh premium-grade or higher-octane gasoline.

If I owned a modern (and expensive) automobile, I would not use that fuel in its engine. It seems like a lot of risk for the engine to run it on a home-brew fuel mixture.

On the other hand, exactly what you are going to do with 42-gallons of water-gasoline-ethanol mixture is another problem to solve.

jimh posted 09-21-2015 09:49 AM ET (US)     Profile for jimh  Send Email to jimh     
I don't have any idea what might happen to the mixture of gasoline and water-ethanol in the Pate Plastics fuel tank, but it couldn't be beneficial for either the fuel or the Pate Plastics fuel tank.
Tom W Clark posted 09-21-2015 10:48 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
David -- I have just been through this same scenario with my Revenge 25. I had to decant about 25 gallons of fuel out of the boat's 140 gallon fuel tank (which was full) to get all the water/ethanol mixture out

I removed the fuel withdrawal tube plate because its gasket had failed and this is over the very stern of the tank and allowed a very good visual inspection of the interior of the tank as well as an easy way to suck out the very little bit of debris from the very bottom of the tank with a wand I made with a three dollar length of 3/8" aluminum tubing from the hardware store stuck in the end of a primer bulb/fuel hose assembly

I had the bad fuel stored on various 5 gallon jerry cans and 6 gallon portable outboard fuel tanks. I very carefully siphoned off the gasoline into a clean container and then added that to my trucks fuel tank, passing it through a filter to insure particulates did not get into my truck's tank

As to the octane of this fuel, I had no way to measure it but I can confirm that the electronically fuel injected V-8 in my truck couldn't care less; it ran just like it does with a fresh tank of gas for the gas station. If I were you, I would not worry about it

The ethanol/water mix in your Pate tank however had probably damaged it beyond it being useful for a boat. I was amazed how nasty the ethanol/water mix was on almost any plastic or rubber it came into contact with including the o-rings around the drain tubes in my boat

Jerry Townsend posted 09-21-2015 01:35 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
David - If you were using an ethanol mix, the ethanol has been saturated with the water. The water at the bottom of the tank tells you that the ethanol is saturated with water. As such, the water/fuel in your Pate tank is useless and should be discarded. Contact a business that changes oil and they may be able to help you get rid of it.

If you were using non-ethanol gasoline - the gasoline is still good and can be used. The separation of water and gasoline is natural because water is heavier. --- Jerry/Idaho

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