My alpha did it once. After full wot with boost and shut down by tether. Wouldnt start for an hr on hill I opened gas cap relieved pressure and it fired up..... suction? I dunno if it's possible but that's my story.
I have also noticed that my alpha gets lots of vacum in gas tank. Seems like a check valve not function properly. If your sled keeps the atm pressure for the riding area inside the gas tank, and you trailer the sled to lower elevation, the pressure inside the tank will be lower then the atm pressure. Meaning more vacume in tank. If the gas inside the tank gets cooled down by the hauling, it will decrease the pressure even more inside the tank.
Next time, try to release you gas cap when you get home, and listen if there is air going into the tank when opening cap. Then try to start it.
