Why is my fuel pump fuse blowing?

I have a 97 Grand Prix GTP and for my fuel pump fuse keeps blowing. I just paid $75 to have my car towed and had a diagnostics test run on it and the problem was that the fuel pump fuse blew. We put a new one in and it started right up. Tonight it blew again and when I put a new one in, it started right up again. I made it home but I'm afraid its gonna blow again. The mechanic said he looked the whole car over and couldn't find a reason for it blowing. The only thing I can possibly think of is the fact that I got my subs and amp hooked up 2 weeks ago. It never did this before I had it hooked up so it makes me think that has something to do with it. When I turn the power to my stereo off it makes this loud b sound. Does anyone know why the fuse keeps blowing? Do I need to unhook my amp? And should I make the guy that hooked it up come back out and fix it? I called him and he said the amp has nothing to do with the fuel pump fuse so I don't know if I'll be able to get him to come out?