1989 Chevy Suburban will not start

I bought the rig knowing that it was possibly a timing problem. The previous owner stated that when he was driving it it began to loose power and started overheating. He did state that he turned it off as soon as he recognized that the problem was getting serious. I have tried to start it all it will do is crank with with a whoof sound coming out of exhaust every so many revolutions. Which would indicate to me that it was loading up on fuel? Do you think it jumped time, and if so what would be the easiest way to determine this? Thx.