instantly blowing 30A "engine" fuse...HELP!!!

well the subject line says it all... i was driving along and all the sudden everything went dead. I found that the 30A fuse marked "Engine Fuse" was melted down. I replaced it with another 30A fuse and pop, it melted down again. I have not done anything to this car electrically, what could it be?

do u replace it juss like that?(with the battery on) try disconnecting the battery for a while then replace. see wat happens

I kept blowing the same fuse when my CAS wiring was shorted out after the throttle cable rubbed through it. Could be ANYTHING though... Most likely going to be something similar, one of the ECUs input/outputs