ethanol in gas causing problems?

I have been seeing more questions about hard to start when hot, rough idling, boat stopped running, etc and just wondering if the ethanol in gas is partially or fully to blame. the thread titled 3.0 hard starting has a post with an explanation of the effects of ethanol in fuel and what can happen. the temps are rising and more boaters are getting out now. rocky road submitted this. take it for what it is worth to you.

"ETHANOL AND VAPOR LOCK

Short description:
When the engine compartment becomes hot either by climate or idling, and you use ethanol-blend gasoline it can cause excessive vapors in your fuel line and starve the engine of fuel. The engine can run poorly or stop and will not run until the fuel condenses.

THE PROBLEMS

Vapor Lock

Fuel containing 10% ethanol is called E10. If you have ethanol in your gas, you run the risk of creating vapor lock because of excess vapors.

Ethanol ?boils? at 87?F (at normal atmospheric pressure) and turns from a liquid to a gaseous state. By comparison, most automobiles have their fuel pump in the gas tank, so the whole system remains under pressure unlike boats whose fuel tanks are vented. In a closed system, the higher pressure raises the flash point of the ethanol reducing the amount of vapor that is produced. In addition, most automobile fuel lines are outside of the vehicle allowing them to stay cooler.

Since most boat fuel lines are in the enclosed space (sometimes even insulated) of the engine compartment, normal ventilation will not cool the fuel significantly enough to avoid the potential problems of vapor lock. Furthermore, since the fuel pump in a boat is mounted on the engine (versus a car where the pump resides in the tank) the action of the pump can reduce pressure in the tank to below atmospheric pressure and further reduce the flash point.

Boat engineers are aware of this problem and are reducing the likelihood of this occurring by reducing the suction required by the fuel pump, minimizing hose fittings and bends, and including a quality anti-siphon valve. In existing boats, fuel lines and filters should be kept as low in the boat as possible and tank vents should be cleaned and open.

Heat Soak

Most boats have ?forced? ventilation. Air moves through the engine compartment when the boat moves forward. Heat soak happens after you have been at high RPM and then stop or drift on idle for a while. Because of heat soak the engine compartment will rise to a point where the ethanol will boil

THE CURE

To prevent vapor lock (i.e. boiling ethanol):

Make sure the engine compartment has adequate ventilation.
Relocate fuel lines to be low in the bilge. (The bilge is cooler because it is in direct contact with the water.)
Monitor the engine compartment temperature.
Add (or turn on) engine room blowers.
Keep the tank vent clean and unobstructed.

Re: ethanol in gas causing problems?

Ethanol ?boils? at 87?F (at normal atmospheric pressure) and turns from a liquid to a gaseous state.

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You know,

A little information goes a long way......even if it's wrong.

The boiling point of Ethanol it 78.3 C that makes it a little over 170F.

The boiling point of gasoline on the other hand can be as low as 100F for winter blends of fuel. We usually don't have "Winter" gas in the boat tank when we store it (although we could)

Addition of ethanol doesn't appreciably affect the vapor pressure of gasoline.

E10 isn't a big deal unless you have fiberglass fuel tanks. Then it's a problem. I wouldn't own a boat with fiberglass tanks regardless of the fuel used.


Cheers,


Rick

Re: ethanol in gas causing problems?

Yea, I like how "boiling point" and "flash point" became interchangable terms right off the bat.

Re: ethanol in gas causing problems?

Living in MN we have had ethanol forced upon us for years. The only problem I have is the fact that this alternative fuel even exists and the politics surrounding it when it is not wanted.

Re: ethanol in gas causing problems?

We have had ethanol gas for a very long time in my area. All of my stuff runs fine on that type of gas.
Supposedly e10 wears out fuel lines quicker. This might be true but I have not noticed this to be a problem. I even own a 1967 Chevelle that?s been in the family a very long time still running its original fuel lines. My dad has an old pick up that sat for close to two years with half a tank of gas. We rebuilt the carb threw a fresh battery in and fired it up. He used all the gas in it before refueling. He still owns and drives that truck to this day with no issues.
I think most of the time people have a carb issue they can?t figure out and just blame the e10.

Re: ethanol in gas causing problems?

I've been running gasoline with MTBE and ethanol for as long as it's been available. ( ethanol replaced MTBE which was banned several years ago)

I have run E10 in everything I own and have never had a problem.

Some editorial writers have claimed that ethanol has something to do with RVP (Reid Vapor Pressure) of gasoline when it's really the "Winter" gas that has the higher RVP.

Mercury has known this for quite some time.

If you think you might have a problem with "Vapor Lock" have a look at Mercury SB 99-7

http://www.boatfix.com/merc/Bullet/99/99_07.pdf

Vapor lock gets blamed for a lot of other problems.....

Regards,


Rick

Re: ethanol in gas causing problems?

"ETHANOL AND VAPOR LOCK

Short description:
When the engine compartment becomes hot either by climate or idling, and you use ethanol-blend gasoline it can cause excessive vapors in your fuel line and starve the engine of fuel. The engine can run poorly or stop and will not run until the fuel condenses.

THE PROBLEMS

Vapor Lock

Fuel containing 10% ethanol is called E10. If you have ethanol in your gas, you run the risk of creating vapor lock because of excess vapors.

Ethanol ?boils? at 87?F (at normal atmospheric pressure) and turns from a liquid to a gaseous state. By comparison, most automobiles have their fuel pump in the gas tank, so the whole system remains under pressure unlike boats whose fuel tanks are vented. In a closed system, the higher pressure raises the flash point of the ethanol reducing the amount of vapor that is produced. In addition, most automobile fuel lines are outside of the vehicle allowing them to stay cooler.

Since most boat fuel lines are in the enclosed space (sometimes even insulated) of the engine compartment, normal ventilation will not cool the fuel significantly enough to avoid the potential problems of vapor lock. Furthermore, since the fuel pump in a boat is mounted on the engine (versus a car where the pump resides in the tank) the action of the pump can reduce pressure in the tank to below atmospheric pressure and further reduce the flash point.

Boat engineers are aware of this problem and are reducing the likelihood of this occurring by reducing the suction required by the fuel pump, minimizing hose fittings and bends, and including a quality anti-siphon valve. In existing boats, fuel lines and filters should be kept as low in the boat as possible and tank vents should be cleaned and open.

Heat Soak

Most boats have ?forced? ventilation. Air moves through the engine compartment when the boat moves forward. Heat soak happens after you have been at high RPM and then stop or drift on idle for a while. Because of heat soak the engine compartment will rise to a point where the ethanol will boil

THE CURE

To prevent vapor lock (i.e. boiling ethanol):

Make sure the engine compartment has adequate ventilation.
Relocate fuel lines to be low in the bilge. (The bilge is cooler because it is in direct contact with the water.)
Monitor the engine compartment temperature.
Add (or turn on) engine room blowers.
Keep the tank vent clean and unobstructed.

Click to expand...

The above is full of misinformation.

When the engine compartment becomes hot either by climate or idling, and you use ethanol-blend gasoline it can cause excessive vapors in your fuel line and starve the engine of fuel. The engine can run poorly or stop and will not run until the fuel condenses.

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This occurs on any gasoline engine and is not caused by ethanol. Gasoline has a much lower vapor pressure than ethanol and will readily evaporate at room temperatures, let alone a hot engine compartment. Vapor lock is a common occurrence on carbureted engines and always has been since they started using gasoline in engine around the 1890's

Fuel containing 10% ethanol is called E10. If you have ethanol in your gas, you run the risk of creating vapor lock because of excess vapors.

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Ethanol was introduced many many years ago, in fact the Germans used pure ethanol in engines during world war II. In the 1970's during the so called "oil crisis" distributors (no oil companies) began putting ethanol into gasoline to save on oil and to reduce smog. If it was 10% it was by law to be called Gasohol. The USCG did a study in the early 80's of this and found that almost every pump they got gasoline from no matter where it was located had ehtnaol (actually ethyl alcohol) in it. So in 86 or 87 they, ABYC, SAE and NFPA got together and changed the requirements for marine fuel hoses to be more alcohol resistant.

But gas has had alcohol in it for many years, along with MTBE and other additives.

Ethanol ?boils? at 87?F

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Someone already addressed this issue.

Furthermore, since the fuel pump in a boat is mounted on the engine (versus a car where the pump resides in the tank) the action of the pump can reduce pressure in the tank to below atmospheric pressure and further reduce the flash point.

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It is true that putting th fuel pump in the tank reduces the chance of vapor lock. But putting the pump in the tank also pressurizes the full length of the fuel line and any leak would spray all over the inside of the boat. Plus that a leak in a pressurized system would drain the entire contents of the fuel tank.

So pumps are required to be on the engine. The pump sucks fuel to the engine. If you have a hole in the fuel line or fittings, it sucks air and the engine stops. Very little fuel leaks into the boat, if any at all.

Boat engineers are aware of this problem and are reducing the likelihood of this occurring by reducing the suction required by the fuel pump, minimizing hose fittings and bends, and including a quality anti-siphon valve. In existing boats, fuel lines and filters should be kept as low in the boat as possible and tank vents should be cleaned and open.

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Partly true partly false. Reducing the number of fittings and bends does reduce the possibility of leaks. Most fuel leaks are at fittings. It is a myth that anti-siphon is required on all boats. Anti-siphon valves can be eliminated entirely simply by mounting the tank fuel outlet lower than the fuel inlet on the engine. The USCG only requires an anti-siphon valve if the fuel outlet on the tank is level with or higher than the fuel inlet on the engine. That is why fuel tanks and lines are kept as low as possible.

Tanks are vented to prevent pressure from building in the tank. The recent EPA initiative to have pressurized systems in boats failed for that very reason. Having a pressurized system can turn a boat into a bomb.

Most boats have ?forced? ventilation. Air moves through the engine compartment when the boat moves forward. Heat soak happens after you have been at high RPM and then stop or drift on idle for a while. Because of heat soak the engine compartment will rise to a point where the ethanol will boil

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Forced ventilation on boats is required for only one reason, to keep any fuel vapors in the engine compartment from every reaching the lower explosive limit (LEL) which is the point at which vapors ignite. Studys done by ABYC and the EPA have shown that on an operating engine with natural ventilation (blower not running) the temperature rarely exceeds 130 deg F. Even in Florida where they did the research. However, ABYC and others have recommended that engine ventilation be over sized, simply because newer engines require more air to run efficiently and not produce as much carbon monoxide.

Make sure the engine compartment has adequate ventilation.
Relocate fuel lines to be low in the bilge. (The bilge is cooler because it is in direct contact with the water.)
Monitor the engine compartment temperature.
Add (or turn on) engine room blowers.
Keep the tank vent clean and unobstructed

Click to expand...

All of this is good advice but for other reasons.

Carbureted engine, especially in warm climates have always been notoriuos for vapor lock. Engines with fuel injection and electronic control modules have almost eliminated vapor lock. Putting the pump in the tanks would further help the vapor lock issue but is dangerous on a boat with out special precautions being taking.

Mastercraft a ctually has such a system that was ok'ed by the Coast Guard about 10 years ago. But they had to use special fuel hose and components, and make fuel lines as short as possible and install alarms that would warm of any problems or leaks. All which made the complete engien fuel system package a lot more expensive than the conventional setup. As far as I know they have not had any significant problems, except the cost of repairs is much higher because it is one of those "no owner serviceable parts" deals. The Coast Guard required it to be factory or dealer serviced.

!0% ethanol is very common and has been for years. Seen more often today is E15 or 15% ethanol. The EPA is considering E85 which would be 85% ethanol. All of these are bad on boat engines, not because they cause vapor lock. They are bad because they cause serious deterioration of fuel system components.

Here is an article I wrote on ethanol several years ago. http://newboatbuilders.com/docs/Ethanol.pdf

Re: ethanol in gas causing problems?

Engines with fuel injection and electronic control modules have almost eliminated vapor lock.

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Well, not entirely..... Mercury has had some problems with vapor lock in hot (EFI/MPI) engine compartments that the Cool fuel system and continuous running blowers did solve for the most part.

Most of the Reformulated gasolines today also have further solved the problems by having far lower RVP than previous fuels. The CARB and EPA continue to lower Vapor Pressure to lower emissions from evaporation. CA Reformulated gasolines now have RVP's as low as 7 psi (AVGAS has been 7psi RVP since at least the the 1950's but for different reasons.)



Thanks for posting your Excellent article!

Also, that boat building site, http://newboatbuilders.com/ just about answers every thing anyone ever wanted know about boat building, ABYC, CG regs!


Cheers,


Rick

Re: ethanol in gas causing problems?

HT32BSX115 said:

Thanks for posting your Excellent article!

Also, that boat building site, http://newboatbuilders.com/ just about answers every thing anyone ever wanted know about boat building, ABYC, CG regs!


Cheers,


Rick

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I agree, LOTS of great information there.

Re: ethanol in gas causing problems?

If ethanol is so bad, how come my boat, after sitting for 6 months of cold & winter weather, started this spring with 4-5 pumps of the throttle? And it's a carburated engine. Granted I had to prime the carb, but it started on a dime. Vapor lock? never happened.

Re: ethanol in gas causing problems?

Yeah.....it pretty much doesn't happen much. (Vapor lock pretty much NEVER happens to anything started cold......unless it's on fire!!)

E10 for the most part doesn't cause many problems. It's blamed for most problems though.....

Now if we go to E15+ ......well, that'll probably be a different story.....

Re: ethanol in gas causing problems?

HT32BSX115 said:

Now if we go to E15+ ......well, that'll probably be a different story.....

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So far, there isn't a marine engine that will run on E15. ............ For very long.

Re: ethanol in gas causing problems?

Sea Wolf, that's because you are a Master Chief and when I was in the Coast Guard I was lways told that Master Chiefs talk to God. So you have an in.

Thanks Rick and Don

Unfortunately, I apparently violated the rules and the Chief of the boat took my web site off my signature block.

Re: ethanol in gas causing problems?

Peter Eikenberry said:

Sea Wolf, that's because you are a Master Chief and when I was in the Coast Guard I was lways told that Master Chiefs talk to God. So you have an in.

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When I was in the army that was the belief about Master Sgts. and Sgt. Majors. They have a bat phone that goes straight to God so they can answer God's questions.

Re: ethanol in gas causing problems?

I might add, I have since done further research into this. Ethanol does raise the Reid Vapor Pressure of gasoline about 1%. That would seem to support the posters argument, however, the fuel manufacturers add other compunds that lower the RVP. The US EPA sets maximum RVP limits for gasoline in the US which cannot be exceeded. So any additives such as oxygenates (ethanol is one, MTBE is another) cannot raise the RVP more than the EPA standard. The EPA is also looking at further lowering the RVP. The lower the RVP the lower the evaporative emmissions. Also an added benefit is less chance of vapor lock.

Re: ethanol in gas causing problems?

thank you to the OP