Nissan Repair: help, amp fuse, fuse box

Question
every ime i put a fuse into the fuse box under the hood it blows (fuse 75A) the alternator has just been replaced, it turns over but will not catch

Answer
Shay,

First off the 75 amp fuse is probably the one for system power and without it the car will not start.  The engine will turn over but without computer management and a coil no dice.  I would check the alternator for correct wiring, excessive output (like a run away regulator) and the battery for s shorted cell.