3320 tractor won't start - cranks but won't start

hello everyone
I have a 3320 tractor that won't start. It looks to be getting fuel up to the injectors. It does have compression. the built in air compressor acted as if it locked up and killed the engine so i let the tractor sit for about an hour. I then tested it and it started so i thought everything was ok. I didn't actually use the tractor at that time other than starting it and turning it off. When I went back to actually use the tractor it wouldn't start. anyone have any ideas?