1998 gmc k1500 5.7L. installed new fuel pump assembly. one of the connectors was different so i spliced a new connector in to fit the one (one of two, the other matched up) on the top of the new fuel pump. strapped the tank back up, connected the battery, cycled the key and did not hear the pump engaging. got the voltometer out on the connector i spliced - there are 4 prongs, 2 are grounds, 1 is power to the pump, the other is sender signal. there is no reading for the gray wire which is pump power so obviously the pump isnt engaging. any idea what could cause this?