I just bought a 2000 explorer 400 4x4 from a guy @ work. He told me that he was running it the last time he had it out and it quit on him. He said that he changed the spark plug but just couldn’t get it to run again. When I got it home I tore all the plastic off it to make it easier to work on and get to everything. It seems to be getting spark but won’t fire even after putting some gas in the jug. He told me that he recalled that when this all started he recalls that it overheated too. Doesn’t seem to be any coolant in the radiator either. Oh yeah, it seems to have good compression too. I put my thumb over the cylinder port and cranked it and it’s hard to keep my thumb over the hole. I also pulled the flywheel to make sure that the woodruff keys was ok. There was some liquid (seemed to be coolant) in the recoil housing too, if that tells a story too. I also checked the crankcase dip stick to see if was overfilled but its not.