Fuel pump probelm?

my fren and i had to change the 2 freeze plugs in the back of his motor he has a 97 silverado 1500 after we put on the trans the fuel pimp started to make that noise wen its on with out the keys in the ignition only way to make it stop is to disconnect the battery but once u reconnect the battery the fuel pump starts goin with out the keys in the iginition .. we tried puting the key in starting and turning off the truck taking out the key but still fuel pump still goin .. tried taking out fuel pump relay but no luck it still kept on making niose.. any one have had this problem .. the fuel pump is only 2 months old so it cant be broken