New to atvs please help

Ok so bare with me, I am a newbie. I bought a 2003 magnum 330 4×4 that wasn’t idling. So when I started opening her up I noticed a lot of hoses that weren’t connected. So I cleaned the carb connected the hoses and got her going. Now she’s backfiring when I go to shut her down? Then I noticed that the vacuum hose from the carb to the fuel pump is disconnected and capped! Any idea why?