When I bang on the gas tank with a rubber mallet - the engine fires a little, but dies right out and does not get going. When trying to start it without banging the gas tank - it does not fire at all. Seems like a fuel pump problem doesn't it?

I was talking to the auto parts person who I ask about car problems and he was giving a rundown of no fuel problems and mentioned the fuel pump - I said, "Ya know its funny - I just got a full tank of gas". He said 90% of the time when a fuel pump goes - it is after a full tank of gas - it stirs something up and gets caught in the pump. He showed how the whole pump assembly part is $130 and just the pump part is $80 - one has to install the $80 pump part into the assenbly to save that money. Any thoughts?