Ethanol Fuel Seperation Problems

[NYBo]

Re: Ethanol Fuel Seperation Problems

The idea of fuel condensing because of cold gas tanks doesn't make a lot of sense. The tank will change temperature with the air. Now, if it's full of gas, it won't change temperature quickly enough, but there is also not much room for air anyway. I don't think there is a lot of air movement in and out of the tank through the vent- it's just too small. I have about 3/8 of a tank of three-year-old gas in my boat. Motor started and ran just fine.

 

[109jb]

Re: Ethanol Fuel Seperation Problems

The idea of fuel condensing because of cold gas tanks doesn't make a lot of sense. The tank will change temperature with the air. Now, if it's full of gas, it won't change temperature quickly enough, but there is also not much room for air anyway. I don't think there is a lot of air movement in and out of the tank through the vent- it's just too small. I have about 3/8 of a tank of three-year-old gas in my boat. Motor started and ran just fine.

First, lets say you have 1/4 tank of fuel. Then you also have 1/4 tank of fuel that also has to change temperature. Kind of like sticking a metal spoon into your ice cream. The spoon gets much colder than the air temperature, even the part not in the ice cream. The tank will tend to change temp aat the rate the fuel doe, not the rate the air does.

Second, air does move in and out of the tank. Lets say you have that 1/4 tank of fuel again. Then you have 3/4 tank of air. As it heats up, the air expands and moves out. Now night comes and lower temperatures and the air gets sucked back in through the vent.

As I said, believe what you want, but my personal first habd experience is what I will believe.

 

[Rscardina]

Re: Ethanol Fuel Seperation Problems

From a Merc mechanic:

"This past year at service school, I was privy to learn about Mercurys View with regards to Ethanol in fuel.

Here goes. <---gonna skim through it.

Mercury remains very active in developing a thorough understanding of important issues and environments in which our products must operate.

What are ethanol and ethanol-blended fuels?

Ethanol for fuel is highly refined beverage(grain) alcohol, approximately 200 proof, that can be produced from natural products such as corn, sugarcane and wheat. This alcohol is denatured and NOT safe to drink.

Does Ethanol afffect horsepower or fuel efficiency?

Ethanol has a heating value of 76000 BTU per gallon, which is approximately 30% less than gasoline's heating value. The result is E-10 or 10% Ethanol blended fuel should yield slightly lower MPG...roughly 3%.
The octane rating of pure ethanol (200 proof) is about 100 and is therefore useful in elevating octane value of gasoline. In E-10 blends the presence of ethanol provides abaout 2.5-3% of the overall octane rating. The effect on engine horsepower is determined by the octane result of the blended fuel.

Are Mercury engines compatible with ethanol fuels?
The fuel system components of Mercury engines will withstand up to 10% alcohol content in gasoline.
E20 is NOT acceptable in Mercury product.
E85 can cause engine damage in current Mercury products.

What about fuel system components on boats?

Check with your boating manufacturers with regards to acceptable fuels. Fuel tanks and lines may be suseptable to damage from E10 and higher. This may cause clogged filters or leaks or engine damage.

How does ethanol affect fiberglass fuel tanks

Prior to 1991 fuel tanks may NOT be compatible with E10 or greater blends of fuel. Resins can be drawn from the fiberglass and distributed through the fuel system.

Are older fuel lines and gaskets prone to failure

During the 1980's, many rubber components for use in t fuel systems were developed to withstand exposure to fuels containg ethanol. If rubber components in a fuel system are suspected to be of this vintage or older its advisable to replace them. Watch for swelling or deterioration.

Now what everyone worries about...Phase separation and how to deal with it

If signifigant amounts of water are present in a fuel tank with gasoline that contains ethanol, the water will be drawn into the fuel until the saturation point is reached for the three-component mixture of water plus gasoline plus ethanol. Beyond this level of water, phase separtion could cause out of the ethanol and water to separate from the build fuel and drop to the bottom of the tank, leaving gasoline with a signifigantly reduced levle of ethanol in the upper phase. If the lower phase of water and ethanol is large enough to reach the fuel inlet, it could be pumped directly to the engine and cause significant problems. Even if the ethanol water phase at the bottom of the tank is not drawn into the fuel inlet, the reduced ethanol level of the fuel reduces the octane rating by as much as 3 octane numbers...this may cause engine problems.
The level at which phase separation can occur is determined by a number of variables, including the amoount of ethanol, the cmpsition of the fuel, the temperature of the environment and the presence of contaminants. It is VERY important that:

The system is inspected for signifigant quantities of water in the tank before using gasoline with ethanol.

To limit exposure of the fuel tank to excess water.

If phase separati0n has occurred, it is necessary to completely remove all free water from the system and replace the fuel before continuing operation. Otherwise, engine problems can occur.

Are there additives to combat phase separting or to reverse the process?
*** No ***

Is there a way to limit the condensation in the tank?

Keep the fuel tanks as full as possible, this will limit the amount of air and tank space above the fuel which may lead to condensation.



Just figured i would post something that the manufacturers are telling the mechanics..

Some is on point to alot of others opinions in this thread..

 

[jmarty10]

Re: Ethanol Fuel Seperation Problems

I think the real issue here is..............how long can your boat sit with e-10 in it before you have to start worrying about fuel/e-10 issues. 2weeks, 3weeks, 1 month, 6 months, 1 year, 2 years. Lots of good info on fuel/e-10 issues

 

[45Auto]

Re: Ethanol Fuel Seperation Problems

I don't think there is a lot of air movement in and out of the tank through the vent- it's just too small.

How fast do you think your engine can suck gas out of your tank? Any V8 will easily burn 20-30 gallons per hour. Your gas tank vent has to be able to flow at LEAST that equivelent volume of air.

 

[QC]

Re: Ethanol Fuel Seperation Problems

Does Ethanol afffect horsepower or fuel efficiency?

Ethanol has a heating value of 76000 BTU per gallon, which is approximately 30% less than gasoline's heating value. The result is E-10 or 10% Ethanol blended fuel should yield slightly lower MPG...roughly 3%.
The octane rating of pure ethanol (200 proof) is about 100 and is therefore useful in elevating octane value of gasoline. In E-10 blends the presence of ethanol provides abaout 2.5-3% of the overall octane rating. The effect on engine horsepower is determined by the octane result of the blended fuel.

Although there is some good info here, there are also some inaccuracies. Clearly the guy who wrote this confuses energy content and Octane. They are not equivalent!! To say that an engine would lose 3% MPG on E10 (it probably would) and then say it would also have more power is completely and utterly contradictory. Power from fuel IS efficiency.

His 3% loss of MPG is fairly accurate because E10 contains less btu/gallon than 100% gasoline. My calcs say 111,100 vs. 115,000 which is 3.4% . . . The only way to get more power from an engine by using higher Octane is to push the knock limit by advancing timing or raising compression or boost or two out of three or all three. (PM me with email addy and I will send source document. Slightly too big to attach)

So unless the engine being discussed has a knock sensor and active timing/fuel rate management to push performance to the point of knock, then no power increase can be realized from increasing Octane. This is true no matter where you get the Octane improvement.

So, no more power for any mechanical engine and almost all of the electronic engines. In fact according to an email I received from Mercruiser (not Mercury) their electronic engines do not use their knock sensors for active fuel and timing management, so not gonna get nuttin' from Octane increases without manually tweaking

There is my confrontational post in this relatively mild discussion

 

[Beefer]

Re: Ethanol Fuel Seperation Problems

The world is flat
The world is round;

We came from apes
We came from Adam & Eve;

Tomato
Tamata

Someday this will be figured out. In the mean time, I'll err on the side of caution, and shy away from a 'potentially' problematic fuel mixture. I'll stay with what's known to be a reliable fuel.

 

[sasto]

Re: Ethanol Fuel Seperation Problems

One thing is for sure.........I learned alot from this post. Even though I had to read it a half dozen times to grasp it. Thanks guys!

 

[45Auto]

Re: Ethanol Fuel Seperation Problems

For the ones who don't get condensation in their tanks:

Do you get condensation on your car windshield? I come out every morning to go to work and have to run the windshield wipers and defroster so I can see out of the windshield. It's covered with water, I would estimate maybe a quarter of a cup a day. It's in the mid-80's in the morning at 6 when I come out, the water from the moist air condenses onto the windshield every night. I would guess that the windshield surface area is about the same as a half empty fuel tank on a car or boat.

I can understand how the exposed inner surfaces of my metal gas tanks rust over the summer. The fuel (and tank walls) cools off overnight and acts just like my car windshield. A quarter of a cup a day over the summer would easily give me the gallon or two of water (see post #39 above) that I see in a car gas tank after it sits up for a year or so.

 

[edwardh1]

Re: Ethanol Fuel Seperation Problems

Merc and Yamaha web sites disagree on the use of filters.
Yamaha web site says use a 10 micron water sep fuel filter and the Yama dealers here do that.
merc says an additional filter will restrict fuel flow.

who to believe??????

 

[Mark42]

Re: Ethanol Fuel Seperation Problems

For the ones who don't get condensation in their tanks:

Do you get condensation on your car windshield? I come out every morning to go to work and have to run the windshield wipers and defroster so I can see out of the windshield. It's covered with water, I would estimate maybe a quarter of a cup a day. It's in the mid-80's in the morning at 6 when I come out, the water from the moist air condenses onto the windshield every night. I would guess that the windshield surface area is about the same as a half empty fuel tank on a car or boat.

I can understand how the exposed inner surfaces of my metal gas tanks rust over the summer. The fuel (and tank walls) cools off overnight and acts just like my car windshield. A quarter of a cup a day over the summer would easily give me the gallon or two of water (see post #39 above) that I see in a car gas tank after it sits up for a year or so.

I undestand what you are pointing out. The reason fuel tanks don't get lots of condensation on the inside is they are not continually changing the contents of the tank. Most of the vapor is actually gasoline vapor, and low water content. When the temps change, only a small amount of outside air is sucked in, maybe 1 gallon or so. How much water will condense out of 1 gallon at 100% humidity? About 3/100th of a gallon (at 100% humidity). That small amount will be sloshed around and pulled through the pickup if the boat is used occasionally.

The bottom line is there is not enough exchange of contents of the tank on a daily basis to bring in enough moisture to make enough condensation to amount to anything.

Do the test yourself. Take a 1 gallon empty dry milk jug, put 3 feet of 5/8" vent hose on it. Put it outside where rain will not get in, and check it in a month and see how much condensation there is inside. Might even want to put an inch or two of oil in the jug so any condensation will sink to the bottom and not evaporate.

I can tell you from experience that leaving my gas tanks empty for 7 months out of the year causes no condensation.

People just assume the water found in tanks is from condensation. The fact is gas stations pump water with the gas.

 

[edwardh1]

Re: Ethanol Fuel Seperation Problems

wonder why the national marine manufacturer's association or merc/yamaha have not funded a third party test to see what the answer is?

Are they
a asleep?
b dont care?
c stupid?

Yamaha just in last few years on their web site (since arrivial of ethanol gas, starteted talking about using a water sep filter)

 

[45Auto]

Re: Ethanol Fuel Seperation Problems

When the temps change, only a small amount of outside air is sucked in, maybe 1 gallon or so.

I've got a 20 gallon tank with 10 gallons of gas and 10 gallons of air in it. That 10 gallons of air is going to stay at the same humidity as the outside atmosphere unless the tank is sealed, which it is not.

Do the test yourself. Fill a plain steel tank halfway up with gasoline. Come back in a year and explain how all of the interior walls above the fuel level are rusted and there's a gallon of water in the bottom that wasn't there when you started.

I can tell you from experience that leaving my gas tanks half full for a year causes condensation.

People just assume that the water found in tanks is from the gas station. The fact is that sometimes condensation is the cause.

wonder why the national marine manufacturer's association or merc/yamaha have not funded a third party test to see what the answer is?

Are they
a asleep?
b dont care?
c stupid?

Answer is B. Why should they care? It's a common, well-known physical phenonema that's been known about for centuries. It has been studied intensely for decades in the aviation world because they don't like their motors quitting on them. Do any kind of search on aircraft fuel and it will be one of the top 2 or 3 items. For the NMMA or a manufacturer to do a study on it would be kind of like them doing a study to see if an engine will run without oil. They're not going to waste their money, they already know the answer from a little basic research. Kind of the same thing with the old "airplane on a treadmill" thread. The answer is obvious if you understand the basic principles, but lots of people still don't believe it.

For example, this is from a Civil Aviation Operations Advisory on Aircraft Ground Handling and Servicing:

This is from Exxon Aviation Fueling:

This one is from the Shell Winterizing Your Aircraft:

No big deal if you don't believe it, there's only a couple of guys on here I would trust to fly with anyway!

 

[edwardh1]

Re: Ethanol Fuel Seperation Problems

so would the next step be for the boat manufacturer installing a fitting or connection to allow you to drain/pump water (or all the fuel on smaller tanks) out of a boats gas tank?
or to come from the factory with a boat fuel/water seperator?

 

[45Auto]

Re: Ethanol Fuel Seperation Problems

so would the next step be for the boat manufacturer installing a fitting or connection to allow you to drain/pump water (or all the fuel on smaller tanks) out of a boats gas tank?
or to come from the factory with a boat fuel/water seperator?

Since the gas tank is frequently the lowest part of a boat (sits flat against the hull, under the deck of the boat) it's hard to mount a drain to it. Most quality boats have come from the factory with a fuel/water separator for many years (imagine that!). If your boat doesn't already have one, Iboats will be glad to sell you one for just over $20:

http://www.iboats.com/Fuel-Filter-W...49999350--**********.206133207--view_id.56071

Here's the page from the Mercruiser Operator's Manual on changing it:

 

[edwardh1]

Re: Ethanol Fuel Seperation Problems

yes, some do, some dont- our 1999 3.0 mercruiser had no factory water seperator.

and lots of things are hard to do
- like having a simple heigth adjustment on a boat seat
-or having the ability to raise or lower the shift controls a few inches
- still using wood that rots, in structural places

- boat industry does not work on the "hard" ones.

 

[Mark42]

Re: Ethanol Fuel Seperation Problems

I spoke with an airplane mechanic this weekend about why airplanes have water in fuel problems. He said its from condensation caused by the extreme changes in air pressure and temperature that cause the air in the tanks to flush in and out many times on a single trip. Apparently the changes in temperatures that occur on a single flight causes condensation in-flight, compared to an automobile or boat that only experiences changes in atmospheric pressures as the weather changes.

So the problem with air planes is they operate in an environment that promotes extreme condensation while in use.

To me, that is completely different scenario from what boats experience when in use.

I know very little about air planes, just passing on what a professional had to say about it.

 

[109jb]

Re: Ethanol Fuel Seperation Problems

I spoke with an airplane mechanic this weekend about why airplanes have water in fuel problems. He said its from condensation caused by the extreme changes in air pressure that cause the air in the tanks to flush in and out many times on a single trip. Apparently the changes in temperatures that occur on a single flight causes condensation in-flight, compared to an automobile or boat that only experiences changes in atmospheric pressures as the weather changes.

So the problem with air planes is they operate in an environment that promotes extreme condensation while in use.

To me, that is completely different scenario from what boats experience when in use.

I know very little about air planes, just passing on what a professional had to say about it.

None of which happens to my airplane when it is sitting on the concrete pad in an enclosed hangar and yet I still get water if the tanks are low and it has sat for a while. So apparently the environment inside my hangar promotes condensation too.

 

[Fed]

Re: Ethanol Fuel Seperation Problems

I'm in condensation denial here but I do accept that could happen in some climate or altitude extremes, sounds possible right?
I've had plenty of fuel tanks in boats & cars and even had some with water in them but EVERY time the water was caused by leaking in from the outside. When the leaks were fixed the water stopped. Maybe the climate here doesn't create fuel tank condensation but we do get dew on cars windscreens just not on the inside.

 

[edwardh1]

Re: Ethanol Fuel Seperation Problems

so my question is
where are the industry tests/research/experiments to prove or disprove all these different opinions.
And if water does form/leak into/come with the gas in boat fuel tanks why is not there a pump out line to the tank bottom?

are gas deck tank fill caps certified or tested in any way to prove their ability to keep water out, when like under way or in heavy rain?