put a good fuel pressure gauge on it and see what the reading is (no more than 6.5 at any time on a holley.
pull the brass flat head screw out of the side of the float bowl (with it running or electric pump on) and see if fuel comes out, if it does then shut it off and readjust the float. if no dice pull the float bowl and check the float to see if it floats or if the needle and seat have junk in them causing them to stick.