fuel injection fuse keeps blowing

Working on a 1990 Lumina Euro sport, 3.1 with a/c. Was left on until battery died, then wouldn't jump. Replaced the little black box fuse relay thing next to the jumping terminal and car started on jump without problems, three days later it started blowing the fuel injection relay every time you try to crank it. THinking it is either wiring or the fuel pump. Just looking for some knowledge before I decide to drop the fuel tank and replace the pump. Thanks.