On 23 Sep 2004 12:12:48 -0700, (Matt Lang) wrote:

I find it highly unlikely that there are no Oxygen (O) atoms in gas....

There are, but tiny amounts. Gasoline is mostly hydrocarbon molecules,
which like the name implies, is only hydrogen and carbon atoms. There
are many of different types of hydrocarbon molecules in typical
gasoline. However, there are also trace amounts of other compounds in
there, some of which contain oxygen atoms as well as sulphur, nitrogen,
some metals ...

Steve

With the stuff you get from the gas pump, ya, there is oxygen in the
formula. It is being put there by design for pollution purposes (EPA
mandates) and for economic reasons (sometimes its cheaper to blend straight
gas with something). At a chemical level, gasoline does not contain oxygen.
The key word is formula.

If only the powers that be would quit changing the formula. Carbs are
limited range animals that can't fully handle all that difference. Engines
demand a specific ratio of hydrocarbons to oxygen to produce optimum burn
(or a richer mixture for optimum power). With a constantly changing formula,
it becomes harder or impossible to adjust a carb to produce that optimum.

For more info on gas see
http://auto.howstuffworks.com/gasoline1.htm
http://www.newton.dep.anl.gov/askasc.../chem99658.htm
http://www.smokemup.com/tech/fuels.php



"Matt Lang" wrote in message
om...
I find it highly unlikely that there are no Oxygen (O) atoms in gas....

Matt

"Ken" wrote in message
...
One thing with ethanol is that the stuff contains oxygen atoms along
with
the hydrogen and carbon atoms, where as straight gasoline is hydrogen
and
carbon only. The oxygen tends to lean the mixture entering the engine.
No
matter what carb setting you apply after that, the air/fuel ratio never
gets
back to what it was. A lean mixture will burn hotter and more readily
creates detonation and preignition (4 cylinders inboards tend to have
dieseling problems with the stuff). It can also cause stalling problems.
With cars the oxygenated fuels tends to work ok as the computers and
sensors
keep a good control. With marine engines its a problem.


"Larry Weiss" wrote in message
...
Both of my power boats have developed severe engine hesitation
problems. They run okay at idle but sputter and stall when revved.
My
mechanics have complained that they are seeing this problem left and
right - and are blaming it on the gasoline, which around here (Long
Island, NY) now contains 10% ethanol. I know ethanol is not good for
rubberized fuel lines, but did not know it caused running problems
(unless the fuel lines are deteriorating and clogging). The gas in
each
boat was purchased at a different fuel dock.

If my mechanics are correct, this is a serious regional (national?)
problem. Anyone else experiencing difficulty? Any comments or
suggestions? How can we get gasoline without ethanol in it? How is
the
marine industry addressing this?

Larry Weiss
"...Ever After!"
"a little after..."

"Larry Weiss" wrote in message
...
Both of my power boats have developed severe engine hesitation....
.... blaming it on the gasoline, which around here (Long
Island, NY) now contains 10% ethanol.

Problems we had in motorcycles involved water. Seems that while gas and
ethonol mix fine and ethanol and water mix that ethanol saturated with water
doesn't mix with gas nor burn well.

Larry,

As so often happens in these groups, there is a good deal of less than
complete data. After several decades of working in the test labs of
Detroit let me fill in some of the problems.

Old issue:
Alcohol is a solvent for the "Permatex" that used to seal two-stroke
crankcases. This would allow charge mixture to leak out, air to leak in
during the cycle and the engine would go lean and self distruct. There
was also an issue raised with the alcohol interfering with the lubricity
of the ashless oil causing a breakdown under load. I never saw this
verfied and was told by a lubricant supplier that it was simply false.
This would make sense becuase the engine damage that I surveyed was all
piston damage most likely the result of lean mixture.

Fix - Use an alcohol resistant silcone base RTV sealant during assembly.

Known issue:
All elastomers have some absortion rate of almost all liquids. It is
additive. So, if Hexane make a 4% swell, and butane makes a 2% swell
then expect winter pump gasoline to cause 6% swell. Alcohol swell is
typically 3-4%, so it added to the fuel you should now expect a 10%
swell. That will FU (make less than optimal) a rubber tipped needle and
seat of an old carburetor float valve system in fine style.

Fix - Go find a Grose Jet to replace the rubber tipped needle and seat.
These were made for out labe by a shop in RI (Providence - I think). If
the neat guy that runs the shop is still there, he has data for most
things and can make what you have data for. - Not cheap - Very Good

Little known issue:
But, touched on by one poster. The F/A will be differnet for an -OH
(the family of alcohols) blend fuel than it is with pump grade non-OH
blended fuel. This can and often did cause drivability and performance
issues. Modern cars correct for this on the fly (not goingthere now).

Fix - Older engines can not do this automaticly, but can be corrected
for the 12-20$us that a box of carburetor jets will cost (you can stiil
buy at speed shops). Upsize the main jet(s) in the carburetor until
the engine runs as it should.

Unfortunately, this was much easier to do in a engine dynamometer test
room that I might be in a boat, but I have done it and it takes some
patience and persistance.

Good Luck
Matt Colie


Larry Weiss wrote:
Both of my power boats have developed severe engine hesitation
problems. They run okay at idle but sputter and stall when revved. My
mechanics have complained that they are seeing this problem left and
right - and are blaming it on the gasoline, which around here (Long
Island, NY) now contains 10% ethanol. I know ethanol is not good for
rubberized fuel lines, but did not know it caused running problems
(unless the fuel lines are deteriorating and clogging). The gas in each
boat was purchased at a different fuel dock.

If my mechanics are correct, this is a serious regional (national?)
problem. Anyone else experiencing difficulty? Any comments or
suggestions? How can we get gasoline without ethanol in it? How is the
marine industry addressing this?

Larry Weiss
"...Ever After!"
"a little after..."