engine coolant temp sensor i'm helping someothers with the same problem but its on swapped engine and the signal isn't making back to the ecu i'll be fixing that this weekend but anyway. I went out and unpluged my engine temp sensor(at 5 am) to see if it really made a difference in starting WOW truck wouldn't start pluged it in started right up. Now yours is most likly just not within the correct value so the engine is thinking its warmer than it really is or there is a break in the wire somewhere. 20-30 bucks for one at autozone.

89 2 dr turbo diesel
89/88 "Backwoods sas"