The other day I was around 4500 feet in single digit weather and I had just woken up to melt some snow for the day using a msr whisperlite, shaker jet model, one that hadn't seen any maintenance in quite awhile. I put the pump into a 2/3 full msr bottle of white gas, connected the line to the pump, and pumped about 25-30 times. I turned the knob to let the fuel in the priming cup and instead of the priming cup filling, the stove made noise as though it were already primed and was shooting vapor out. I turned off the gas, tried again, and got the same result. I manually filled the primer cup and lit it, but when the flame died down and I turned the gas on, the blue flame around the jets flickered for a bit then died out. I went through this cycle of attempts about 3 times in 1 hour with no success. I headed home, and lit it successfully as if nothing were wrong, just a few hours later. I'm relatively inexperienced with the whisperlite and after this experience I've vowed to become an expert on it because of how much I depend on it for winter trips, and in all my research I haven't been able to find out what I was doing wrong with my stove or why it wasn't lighting, so I appreciate any thoughts you guys might have on it. A friend of mine thought that the part of the pump that draws gas in wasn't submerged in the liquid gas inside the container so the stove as actually shooting pressurized air out, but I don't have enough knowledge on the workings of the stove to really confirm this. Thanks again!