What kind of plane? I used to have high desert vapor lock on my old
International Travelall...5000 feet and 110 degrees F in the shade. Nothing
I did, and I mean NOTHING stopped the vapor lock problems until!!! I
installed an electric fuel pump at the fuel tank With insulated fuel lines
in the engine compartment and a 1/16" diameter bleed line that vented back
to the tank (so that after sitting for a while any vapor that formed in the
line would vent back to the tank unblocking the line when I flipped on the
fuel pump....the bleed line was insurance as I ran it almost a year with the
tank mounted fuel pump with no problems...The fuel pump seemed to create
enough pressure to collapse or force through any bubbles in the line...but
the heat soaked engine would start more quickly once the bleed line was
installed) I also by-passed the block mounted fuel pump to reduce engine
block heat transfer into the fuel. I put another 100,000 miles on that
vehicle, most of it rock crawling in Utah's Canyonlands in the summer time,
with never even a hic-up caused by fuel vapor blocking the line.

Bruce A. Frank

"Rich S." wrote in message
...
Hi Troop..........

The weather forecast for Idaho today is staggering! 107° F in Boise, 108°
in
Twin Falls and 110° in Mountain Home. Montana is similar with 108°
forecast
in Helena.

Last year, on my way to OSH, I planned my fuel stops to take advantage of
autogas availability. I stopped at Pullman, WA and filled up. As we were
flying past Helena, Montana, the OAT showed 85° at 9500'. Fuel pressure
went
to zero and the electric pump (ahead of the firewall) made no difference.
Within one minute the engine quit. Not rough. QUIT.

I'll spare you the details, but fortunately, as I was about to turn
downwind
for a soybean field, it had cooled off enough to restart. Cautiously, we
climbed and made our way to Helena, 25 miles distant. Draining the
autofuel
and filling up with 100 LL solved the problem.

Unless you are *absolutely* sure that your engine will not vapor lock in
extreme temperatures, do not run autogas. It is not worth the few bucks
difference. Don't worry about the 100 LL fouling a plug or two - your
plane
will still fly.

I am not looking for an discussion or argument about autogas. I use it
regularly in moderate temps. I will not use it when the mercury rises to
these levels.

Keep 'em flying,
Rich S.