will not start

I have a 97 7.3 I purchased from a man that did not run. He told me that he brought it to a mechanic and they told him it was the lift pump . Well I changed out the lift pump and guess what? It still will not start. Its a standard. Need help fast. I'm new to diesels so easy on the diesel...

Thanks for taking the time to take a look at this post, Lord knows I need all the help I can get. 2003 f250 fx4 6.0 This past week I have noticed the truck not quite having the passing power it used to, I wrote this off to the truck having 230k miles. and it still had plenty of take off...