i have an 85 300zx and the interior lights dont work. ive tried to replace the fuse several times but it blows immediately. is this a common problem?

 

all of them? or do the flood lights work?

 

not a common problem. you have a short someplace. Check door light switches they get water in them and corrode. After that have you done any interior work maybe pinched a wire or put in a new radio Think back on what you did may give you a clue where to look