Ok so I have mounted the inline pump and relay, and one of the wires from the relay tap into the stock sending unit wires, but I am having trouble figuring out which wire to tap. I have replaced the in-tank sending unit before, and I believe that the colors of the wires on the new one were different from the old one. The body harness wires are red, white, and brown, and the sending unit wires are purple, black, and white. The Procharger instructions say to tap into the grey wire, which I don't have. So which of these wires do I need to tap for the inline pump?