Some of this is in the stabilizer thread. Gas expands and contracts at
approximately 5 times the rate of water with temperature change. I'd
agree that atmospheric pressure change probably contributes to the
problem too.


JohnH wrote:
On Thu, 31 Aug 2006 09:54:03 -0400, Harry Krause
wrote:

JohnH wrote:
On Thu, 31 Aug 2006 08:42:46 -0400, Harry Krause
wrote:

Shortwave Sportfishing wrote:
I don't know if this has been discussed in the "fuel stabilizer"
thread, but on a email sport fishing discussion list I belong to there
has been a discussion about over-wintering ethanol.

According to Mercury Marine:

"What should be done when storing boats with ethanol-blended fuels for
extended periods?

When preparing to store a boat for extended periods of two months or
more, it is best to completely remove all fuel from the tank."

Ok - so they recommend removing all the fuel in the tank. How do they
suggest this be done? Let's face it, the potential for spills,
explosions and other interesting events increase considerably in this
kind of procedure. And what the hell do you do with, oh say, 50
gallons of gas? How do you store it?

Mercury continues:

"If it is difficult or not possible to remove the fuel, maintaining a
full tank of fuel with a fuel stabilizer added to provide fuel
stability and corrosion protection is recommended."

Ok, this makes much more sense to me. I can see some problems with
this however we'll let Mercury Marine continue.

"A partially full tank is not recommended because the void space above
the fuel allows air movement that can bring in water through
condensation as the temperature cycles up and down. This condensation
potentially becomes a problem."

Ok, so air movement by expansion and contraction of gasoline in
response to temperature changes will make condensation a potential
problem.

I can't believe that 20 gallons of gasoline in a 50 gallon tank will
expand and contract to the point where air movement becomes an issue.
I would think that it's more of a case of barometric pressure, partial
gas pressures of oxygen and humidity that would cause condensation
rather than air movement through the vent.

Yes/No?

Mercury Marine final recommendation continues:

~~Advertisement for Mercury Marine Fuel System Treatment & Stabilizer
and engine shut down procedure deleted ~~

"......topping off the tank until it's full, and capping any openings
to reduce the amount of exchange with the air that might bring in
condensation."

Anybody else besides me think that this isn't a great idea?

Not to mention almost impossible for most of us with smaller boats or
boats with integral gas cap/vent systems?



Good grief.

At the end of the season, I have the dealer dump in enough stabilizer
for the remaining gallons. In the spring, I top off the tank. I've been
doing this for years and years and years, and I've never ever had a
problem with water-infused gasoline.

Have you been using a lot of ethanol flavored gasoline in those 'years and
years and years'?
--
******************************************
***** Hope your day is great! *****
******************************************

John


I did in Florida, where I bought my outboard gas at filling stations,
and I have on occasion up here where I happened to be trailering by a
station with good prices. But I wouldn't say "a lot." I really don't
keep track of what's in the tank, other than the approximate number of
gallons.

Oh, my mistake. I took 'years and years and years' to mean 'a lot'.
--
******************************************
***** Hope your day is great! *****
******************************************

John