Ok, I have an 84 fj60 with an engine that has 120k on it. I have checked and know that I am getting fuel and plenty of spark but my rig will not start for nothing. If I push start it, it will fire right up and go until I turn it off and I can leave it for an hour or so an it will start right back up. But if I leave it for 3 hours, it wont fire up. Whats wrong?