I'm pretty sure temperatures have a lot to do with it. Snowmobiles usually give me fuel system greif unless it's parked either completly empty or completely full, stabil or not. Seems my trucks are more inclined to give me problems if they sit through the heat of summer as opposed to cooler times of the year. It also seems to me that in recent years, gasoline is harder on rubber parts and hoses than it used to be, turning them into sticky mush.
