Jeff 97 Formula

Lately, I've been noticing in addition to the fuel pump prime sounding slow when cold, but I also have a "pop" right after it stops priming (which sounds like it's coming from under the hood). Only when cold, does not happen on warm starts. Any ideas? Thanks!

EDIT - Car is a 1997 Formula with LT1. I also hear a slight hum when I turn the car off after driving it for a bit. The hum lasts about 2 minutes, and can be heard from the rear. And I also smell some gas in that area. Could all of this be an EVAP issue (including the "pop" noise heard under the hood after the fuel pump stops priming when cold)? If so, what should I look at first (canister, or the valve under the hood)