one thing to remember while you're hiking - if you operate it or open it up high, then seal it up, you have negative pressure inside the tank to start with once you drop down lower - this can make it a real bear to get going, because you have to overcome that negative pressure to build up a positive
pressure inside the tank.

I make it a habit to always open the fuel tank cap slightly first to ensure I'm starting with the air pressure for where I'm at first, then close it and warm up the stove with hands, etc, prior to trying to prime and stuff.