Can you help me with this situation?

One of my guy friend from high school started to talk to me on Facebook. It’s been 3 years since we talk and seen each other and somehow I think he knows I am back in town. Well he initiated the conversation and I reply. But every time he reply he takes 2 or 3 days to answer a simple question. He ask me how I’ve been doing and I reply and ask him same. I know he’s online because it shows, but he still won’t reply back. Every time I am on, he seems to go off. I just feel like I am wasting my time.