Ethanol Fuel Seperation Problems

Litetwin4

Petty Officer 3rd Class
Joined
Apr 7, 2010
Messages
78
I suspect that I have an ethanol seperation problem. My engine dies under hard acceleration so I drained the carb bowl, collected the fuel into a glass jar. There is definatley two seperate layers in the fuel. After reading several posts online, I suspect ethanol seperation. How can this be confirmed? How can this be remedied? Will fuel treatment or fuel drier break the fuel up so it can be burned? Any advice is appreciated. Thanks a million.
 

Bob_VT

Moderator & Unofficial iBoats Historian
Staff member
Joined
May 19, 2001
Messages
26,019
Re: Ethanol Fuel Seperation Problems

Just about any old fuel will go bad.

Install a fuel/water separator.

Usually people drain older/bad fuel and use it to mow their lawns.
 
Joined
Oct 22, 2007
Messages
2,598
Re: Ethanol Fuel Seperation Problems

The bottom "layer" you see is water (or mostly water). As already mentioned get rid of the bad fuel, install a fuel/water separator, and start adding fuel treatment every time you buy fuel.
 

jmarty10

Chief Petty Officer
Joined
Aug 6, 2007
Messages
560
Re: Ethanol Fuel Seperation Problems

I'm curious about how old your fuel is. There doesnt seem to be a good answer on what the time frame is about when water seperation occurs in ethanol fuel. Right now, I have marine gas with val-tech that is 3 weeks old. Have about a half tank now and when I first filled tank I put stabil in (red stuff). The remaining gas will be burned on Saturday.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Ethanol Fuel Seperation Problems

You prevent separation by using the fuel before it separates. You protect the fuel by using a fuel system treatment of which there are many (Stabil and SeaFoam to name just two). Adding a water separating fuel filter is very important.
 

109jb

Lieutenant Commander
Joined
Jul 15, 2008
Messages
1,590
Re: Ethanol Fuel Seperation Problems

Th fuel will not separate unless there is water in there also. Water can get in obviously by a leak, bad supply, or from condensation forming on the interior of the tank. You can prevent this condensation by keeping the fuel tank full. This keeps air out of the tank. Humid moisture laden air that cools is the source of the condensation.
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
15,417
Re: Ethanol Fuel Seperation Problems

If its phase separation its a mixture of water and alcohol. Throw the concoction in a bucket of water. If it's phase the fluid will turn white when it comes in contact with the water.

Gasoline and alcohol will not separate over time and you can not condensate enough moisture out of the air to cause phase. The only way separation occurs is if you have free water in your tank. You left the cap off, water got in thru the vent or you where ?dosed? at a filling station.

Contrary to what the additive salesmen wants you to believe, there is no additive that will prevent phase and there is no additive to repair it. If you have a large quantity of free water in the tank the only solution is to remove it. You can drain the tank, or siphon the water off the bottom of the tank if you have a large tank, but you need to get the free water out of the tank if you want to mitigate the problem correctly.
 

ozarkt165

Seaman
Joined
May 18, 2010
Messages
63
Re: Ethanol Fuel Seperation Problems

I can not believe how lucky I have it here in SW MO. Several gas stations around here have ethanol free premium, 20 to 30 cents more than premium blended w ethanol. Well worth the cost. Run it in all my small engines, especially the 2 strokes.
 

Litetwin4

Petty Officer 3rd Class
Joined
Apr 7, 2010
Messages
78
Re: Ethanol Fuel Seperation Problems

I filled my tank with high octane fuel last November and added the recomended amount of fuel stabilizer. The boat was dry docked and stored indoors. I am certain there is no chance that water introduced to the fuel system. I ran it for the first time on July 2nd and encountered poor performance above 25mph. Like I mentioned, the boat starts right up and idles however will not run at higher speeds. The gas does not stink like it is bad. All I know is I will not purchase any more of that brand of fuel.
 

109jb

Lieutenant Commander
Joined
Jul 15, 2008
Messages
1,590
Re: Ethanol Fuel Seperation Problems

... and you can not condensate enough moisture out of the air to cause phase. ...

I disagree. It depends on the venting of the tank and the amount of air space in the tank. A vented tank with a lot of air space and not a lot of fuel in it can condense enough water to cause separation. It doesn't happen overnight, but if it has been sitting a long time it can and does happen.
 

nlain

Commander
Joined
Nov 17, 2005
Messages
2,445
Re: Ethanol Fuel Seperation Problems

If you start good, idle good and run good below 25 and not above 25 mph, I think you need to look at something besides bad fuel, bad fuel should give performance problems at all operating points. You may have low fuel pressure, fuel filter stopped up, if you had that much water in fuel you probably would not start.
 

jmarty10

Chief Petty Officer
Joined
Aug 6, 2007
Messages
560
Re: Ethanol Fuel Seperation Problems

Litewin - try a small fix first like changing your water seperator and draining the gas and replacing with fresh gas. Becasue I am interested in this issue I have seen posts where guys hook up a small 6 gallon portable fuel tank to start diagnosing. But, the easiest fix may be the water seperator?
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
15,417
Re: Ethanol Fuel Seperation Problems

I disagree. It depends on the venting of the tank and the amount of air space in the tank. A vented tank with a lot of air space and not a lot of fuel in it can condense enough water to cause separation. It doesn't happen overnight, but if it has been sitting a long time it can and does happen.

It is highly unlikely according to these two EPA memos and numerous other studies I've read.

Since the solubility of water in both gasoline and air decreases with a decrease in temperature, water can enter a fuel system through condensation when the atmospheric temperature changes. For example, assume a tank containing conventional gasoline contains only one gallon of fuel. Assume also that it is closed while the outside temperature is 100 degrees F with a relative humidity of 100 percent. If this tank is left sealed and the temperature drops to 40 degrees F, water will likely condense on the inside of the tank, and dissolve in the fuel. In order for enough water to condense from the air to cause gasoline-water phase separation, however, there must be approximately 200 gallons of air per gallon of fuel over this temperature drop (100 to 40 degrees). Since oxygenated fuels can hold even more water than conventional gasoline, it is even more unlikely that enough water will condense from the air to cause gasoline-water phase separation.

Water, in the form of water vapor, can dissolve in gasoline. The more humid the air, the faster the water vapor will dissolve in the gasoline. Due to chemical equilibrium, however, assuming a constant temperature, phase separation will never occur if the only source of water is from the air. Only enough water to saturate the fuel can enter the system, and no more. Water vapor, however, dissolves in gasoline very slowly, even at very high humidity. For example, at a constant temperature of 100 degrees F and relative humidity of 100%, it would take well over 200 days to saturate one gallon of gasoline in an open gasoline can (assuming the only source of water is water vapor from the air). Water absorption from the air is far slower at lower temperatures and humidity. (At a temperature of 70 degrees and relative humidity of 70%, it would take over two years to saturate one gallon of conventional gasoline in the same gasoline can.) Again, oxygenated gasoline can hold more water than conventional gasoline, and would therefore take much longer to saturate with water.

http://www.epa.gov/oms/regs/fuels/rfg/waterphs.pdf

Some manufacturers have expressed concern that ethanol-blended gasolines might absorb water vapor from the atmosphere, leading to phase separation. Such problems are of greatest concern for engines with open-vented fuel tanks that are operated in humid environments, such as marine engines. However, evidence for this phenomenon occurring is limited at best. States with extensive ethanol programs, such as Minnesota, have not reported problems with phase separation due to absorption of water from the atmosphere.

Limited testing with ethanol blends suggests that the rate of water absorption from the atmosphere is very slow; it requires several months for open-vented marine fuel tanks to accumulate sufficient water to make phase separation possible, and another source of water is needed before separation will actually occur. Of far greater concern is the accidental introduction of water, by splash or spray, during fueling or the presence of water in the fuel
tank prior to the addition of ethanol-blended gasolines.

http://www.epa.gov/oms/regs/fuels/ostp-3.pdf
 

Fed

Commander
Joined
Apr 1, 2010
Messages
2,457
Re: Ethanol Fuel Seperation Problems

If you don't let any water into your tank then you won't get any condensation in it.
 

Litetwin4

Petty Officer 3rd Class
Joined
Apr 7, 2010
Messages
78
Re: Ethanol Fuel Seperation Problems

The gas sample is definitely seperated with milky colored water. I will siphon the fuel out this weekend and install a water separator. (Filter type with a clear water trap on the bottom)

All of the fuel system components are new including a complete carb rebuild and the system function was confirmed to be ok.

My system has two fuel pumps, an electric fuel pump serves as a booster to the main mechanical fuel pump on the engine. So no problems with fuel pressure. (8psi at the fuel inlet to the carb)

The boat will idle ok but however will not operate when fuel demand is high. Keep in mind the main jets and power valve are located at the bottom of the fuel bowl where the water settles. So when fuel demand is high, water is ingested instead of gas.

I will make the updates, test the boat and let everyone know if there is a happy ending.

Thanks for all of the great feedback. :)
 

Beefer

Lieutenant Commander
Joined
Aug 4, 2008
Messages
1,737
Re: Ethanol Fuel Seperation Problems

If you don't let any water into your tank then you won't get any condensation in it.

You do realize that air contains moisture, and your fuel tank has a vent which not only allows air in, but pulls it in, don't you? :rolleyes:
 

Beefer

Lieutenant Commander
Joined
Aug 4, 2008
Messages
1,737
Re: Ethanol Fuel Seperation Problems

I disagree. It depends on the venting of the tank and the amount of air space in the tank. A vented tank with a lot of air space and not a lot of fuel in it can condense enough water to cause separation. It doesn't happen overnight, but if it has been sitting a long time it can and does happen.

I agree with this post. Phase separation will occur at 0.5% water in fuel. So, (and the math will be really really rough), if you have a 100 gal tank, with 20 gals of fuel in it, you will have 80 gals of air by volume, or roughly 1 cubic meter (probably not too far off for a 100 gal tank at 20% capacity). With a humidity level of let's say 50%, at a temp of about 77 deg F (25 C), you will have 11.5 grams of water per cubic meter. When the temp gets down to 55F/13C (dew point), that moisture will condense. After a few weeks/months, it won't take long for the accumulation of 1/10 gal of water (12.8 oz) to occur. At that point, you will then create what is necessary for phase separation to occur.

And by the way, phase separation can occur as low as 0.3%.
 

Fed

Commander
Joined
Apr 1, 2010
Messages
2,457
Re: Ethanol Fuel Seperation Problems

80 Gallons is only 0.3028329 cubic metres, how many grams of water can you wring out of that and how many times can you wring it out.
Of course your arguement assumes the temperature inside the tank drops to the ambient outside temperature as well.

If condensation was causing water problems inside fuel tanks the seas would be awash with dead boats and the roads would be littered with dead cars.
 

Rezqewr

Cadet
Joined
Jul 28, 2010
Messages
6
Re: Ethanol Fuel Seperation Problems

E-10 ethanol fuel begins to separate the second it leaves the pump. My current job is working in a small engine shop, and 90% of the running problems I deal with are related to phase seperation of E-10 fuel. Honda and Briggs & Stratton do not recommend using fuel over 30 days old.
This can be avoided by using a fuel stabilizer immediately upon fueling. Adding stabilizer to "bad" fuel will not make it "good," however. If you are running a two-stroke, check to see if the oil that you use (pre-mix only) has stabilizer "built-in." Hope this helps.
 

Beefer

Lieutenant Commander
Joined
Aug 4, 2008
Messages
1,737
Re: Ethanol Fuel Seperation Problems

80 Gallons is only 0.3028329 cubic metres, how many grams of water can you wring out of that and how many times can you wring it out.
Of course your arguement assumes the temperature inside the tank drops to the ambient outside temperature as well.

If condensation was causing water problems inside fuel tanks the seas would be awash with dead boats and the roads would be littered with dead cars.

I'm not going to argue with you. Obviously it would be about 1/3 of the 11g, so it would take a little longer. You go on believing what you want.
 
Top