I have to say the problem is in the injection pump. Our 88 had the same problem, started hard when cold then once hot if you turned it off it wouldn't start. I replaced the pump with one off a 1850 I believe, it boosted my power, and now she starts like nothing even in the dead of winter. Also, if you rebuild her...don't use starting fluid on her, I am firm believer that either is like crack for a diesel engine, they just get more addicted to it till the point where they don't start without it. I won't even buy starting fluid to put in our shop I'm scared my brother might put it in the tractors. Thanks, Mike