1990 f-250 7.3 dieel wont start on its own but will start by pulling it.

 

glow plugs could have too much resistance and be bad

 

thanks ill check them

 

2nd glow plugs

 

I gave up on glow plugs on my 6.9 and went to either. Worked great for a few years then the truck was getting harder and harder to start to the point it did take a pull start.
In this case the starter would turn over and crank but it mabey seemed a little slow. Anyways rebuilt the started and that thing starts almost instantly. Over time the starter got slower and slower. Just something to keep in mind if the glow plugs check out ok.

 

either when you spray it in its cold then when your engine starts its really hot and snaps your top piston rings

 

could be sucking air after you shut it off, or glow plug relay,glow plugs, make sure you dont have any fuel leaks on return lines.

 

Is your starter bad?