Any help for batteries and wires?

I assume someone here could help me, I have a old sump pump and I'm replacing the battery, there is 4 wires to connect, 2 say negative but only one says positive, I know there were 2 on each when I unhooked the old battery, I assumed the 4th was positive but when I hook it up to positive Sparks fly and wire gets extremely warm very quickly, do I just hook the one positive wire and ignore the lone 4th wire, it seems to somewhat work with just the one but I'm not POSITIVE (heh...) This is a extremely old system and maybe the 4th wire just isn't required anymore?