injecter problem

I have an old (70's) 580b that sat all winter. I started it up and it ran for about 15 seconds made a clunk and quit running. I thought the engine froze. When I tried to start it it would turn over but not start. I checked to see if there was fuel being delivered to the injectors. There was none, so I loosened the supply lines at the injector pump and no fuel was coming out when I tried to start. Thoughts??? It is a manual shut off and it was in the on position.

Thanks gab

injecter problem