Clicking in the fuel system

Well the mechanic told me that it was the fuel pump and then called me and said it was the injector so I told him to do it and get it fix but he dident. But I looked at the injectors and it look like they never took them off so I think he play me for a fool but the car runs more then better is just the clicking that is annoying and it sound like its comeing from the fuel pump. As I excelerate the clicking goes faster but its not coming from the engine. The noise is under or in the back not the front. Thanks

When I start the car it does not click right away its like a 1min in to the start when it starts clincking. And when I accelerate the car its not that it get louder it just clicks faster but it stops when I hit about 15 to 20mph but when I stop the car it clicks again. The thing is that I just bought the car and I dont know if the guy did something to make the car go faster or something cause thats what the mechanic told me so I call the guy who use to have it and he said he did nothing to the car. I had 3 code reading and one went away when I chang the fuel pump and the other 2 I just replace it was the crank sensor and the camshaft sensor wish is the distributor so I fix all the code but its still clicking and I still have one more light to fix wish is the (ses) and I think I know what it is but what I need help with is the clicking.

Ok thanks