Furnace doesn't work at higher elevations??!!

[dig4gold]

I own a 299 RLS 5er . . . but this is about my old truck camper by S&S. So to all you furnace experts:
I live at 6000 feet, and the furnace works fine in my driveway. But when I go hunting/camping at 9000 feet, it doesn't work right.
I'll explain; It will light just just fine . . . once. Heat coming out, fan whirring away, everything is nice. Then the second time it goes to light (due to thermostat setting), the fan runs and there is no heat!
It is as if the pilot light gets blown out. If I turn it "off" for 5 minutes, and g through the whole starting procedure again, it works fine . . . THE FIRST TIME ONLY!
I took it out and took it in to our local stealership and paid over $100.00 to "fix" it. It works fine at my house (6000 ft), but not at altitude.
The thermo-coupler is practically new, so is the regulator. The shop recommended turning the air adjustment a little and that did not work either.
What is it and what do I do?!

[Threebutchers]

I would expect that there not enough oxygen / air pressure at 9K to fuel the pilot....I would imagine your other burners (stove and furnace) are struggling to burn efficiently as well.

The gas industry sells special burners for altitudes over 4,500'

[dig4gold]

The stove works pretty well. And the pilot in the fridge stays lit.
The shop basically cleaned the pilot, heat sensor, and orafices.

[dig4gold]

But I repeat, it always lights and works great the first time you start it. If pressure was low (why I bought a new pressure regulator) why would it work the first time and not on subsequent lights?

[Threebutchers]

Originally Posted by dig4gold

But I repeat, it always lights and works great the first time you start it. If pressure was low (why I bought a new pressure regulator) why would it work the first time and not on subsequent lights?

I was speaking of Air Pressure - not propane regulator pressure....although, it typically requires a special regulator with lower WC pressure and special orifices on the appliances to overcome lower air pressure and lack of oxygen at high altitudes. High altitudes affect all kinds of combustion and spark generation...small engines, piezo electric spark devices, etc.

I'm not familiar with your furnace - but mine lights the first time via spark generator....when it re-ignites - I assume it uses pilot because I do not hear a spark generator on subsequent ignitions.