I have 2 15" mtx 9500s, and a te1501d amp. It always powers up, but won't always power subs.?

I thought it was my ground, when i move it, places it sometimes works. I was told my power wire could be the problem, but i didn't see any cuts on it. I have a 200 amp alternator, tsunami 5 farad capactor? Could it be the amp not properly working?