holley 1945 losing its prime

if i let my truck set more than couple weeks in summer, couple days in winter i have to fill my bowl with gas before she'll fire off!! ant no problem when its warm weather, lot worse when cold weather! try and spin engine in hopes fuel pump will fill carb but itll run battery down before that might happen! i dont get out every day or 2 but priming carb every time i go out last month or so is getting old! any ideas any body?