Alright guys I have a 88 7.3 idi I bought recently from a co worker they had the truck for almost its entire life so far and never had any major issues with it. It will not cold start but will start everytime after the block heater has been plugged in for a while. I have replaced the glow plugs and have also replaced the glow plug relay. I have done the cycling the glow plugs to allow them to get warmer to attempt to start it and it fails everytime the motor is cold. If you plug the block heater in for a half hour it will start kinda rough but its been about 18 degrees the past two weeks. I want to have confidence that I can take it to work and let it sit and know it will start. So can you guys please help me out

 

I am moving this thread to the proper section

 

Get some WD40 (Do not recommend Starting fluid (Either)) And spray that in the air intake see if that will work. could be it is just too cold and you are getting some minor jelling in the lines you can also put fuel treatment in the tanks.

 

I swear by powerservice in the colder weather.Also check your fuel filter I've had that problem before.