Why is this happening?!!Please help.

Ok, well I found a loose clamp where the old metal fuel line meets the short piece of rubber line just before the filter. I loosened the gas cap and shook the car and the dart made it up my drive way. Ive still got the poblem though. During that time a loud metal hitting metal sound came from the frnt of my motor. I thought my fan was hitting something over and over. It got louder as I revved, and the sound was internal. My stethescope told me it may be the impellor on the water pump hitting the internal shroud. I hope thats all it is. It sounded bad. I relaxed a little when I knew it was not too deep a tap- knock. At least I hope its not. Any ideas?