95LT1Z28

I just hooked up my CSI electric waterpump per Ken Lowrance's directions. When I went to turn the ignition on it immediately blew the fuse by the battery terminal. I am using the 15 amp inline fuse for the battery terminal and hooked up the "hot" wire from the relay to the ignition fuse in the fuse box. I hooked the grounds up to the black wire that is screwed into the chassis on the right side of the radiator. What would make that fuse pop instantly, a bad ground? I have heard some people say to hook up the relay "hot" wire to the AC/Cruise fuse instead of the ignition? Thanks for any help!

Jeff