Completely Lost

[thoant]

96 250
When check engine light comes on engine shuts down. Box shows no codes.
Glow plug light on dash doesn't come on when check engine light comes on.
Doesn't do this all the time but as usual always an inopportune times.
Glow plug Solenoid has been replaced though that didn't correct the problem.
Any ideas? Need this thing running asap!