In a message dated 4/30/2005 5:14:06 PM Pacific Standard Time,
camper@TACTICAL-BUS.INFO writes:

Here in  colorado it is possible to get different blends according to  the
altitude.  But that blending is for emissions and your engine  should run the
same either way if the O2 and AFM and ECU are working  correctly.

I have to respectfully disagree, and I do so with no ill intent and no ill
will. But instead to set the record straight.

You are correct that the high-altitude blend of gasoline has a posative
effect on emissions. However the theory that there's no effect on the  engine's
ability to run correctly doesn't fit the above conclusion.  The idea that a
different blend effects the emissons but not how the engine runs  is flawed. This,
because how the engine is running is directly responsible for  the emissons.
A "correctly" running engine--one running under ideal  circumstances-- will
produce lower emissions than one running under poor  conditions. The
configuration is also then contigent on the blend of gasoline  and the altitude.

The gasoline blended for a specific altitude is concocted with  consideration
to the amount of oxygen in the air. The guy who's stuck in Bryce  is very
possible having a problem related to the fuel system. He stated he can  smell
fuel. Therefore let's say for arguments sake his bus is getting too much  fuel
for the amount of oxygen at the altitude were he is camping. This is likely
because the fuel in his tank is mixed for a lower altitude. In essence the
engine is getting too much fuel to start--it is "flooded." It is running rich we
would say if it were running. or now we can say it's too rich to  start.
Why--because they're ain't enough oxygen to create a favorable  situation for
combustion with the higher octane fuel. (and I'm not willing to  agree that the
difference in the high altitude blend of fuel is soley an issue  of octane.
Although this is certainly the most notable difference to the  consumer since it is
printed at the pump.)

Granted this lack of combustion--or even if he got the engine to
tstart--creates an unfavorable emissions output. But this emissisons  problem is
precisely the same problem that is keeping the engine from  starting: poor combustion.
One is the same as the other.

I would almost agree that if everything is working properly this might not
be a crucial concern. So I'd say if the guy stuck in Bryce drove his Westfalia
off the dealer's lot in 1984 and headed to the Canyon with a lower altitude
fuel  he'd likely be up and running and we wouldn't be here hashing this out.
But 21  years after that bus came off the lot, that extra rich mixture might
just  be enough to leave a guy stranded. And quite frankly it may have been
enough to  leave him stranded him in 1984.

Therefore I still recommend fueling up every 1,000 feet you gain in
elevation. Also a fresh tune up when heading to a higher altitude will  help.

Disclaimer: The fellow in Bryce Canyon could be suffering from a host of
problems. The altitude vs. gasoline is not necessarily it. But it's worth
examining.

Best,
83.5 Westfalia
LA,CA