Dean, If the engine cranks at a good rate, check the glow plugs are getting power at the bus bar while cranking and ensure the stop solenoid is truly retracting (and staying retracted) when the key is on. If that all checks out, then check that the injection pump rack is free to move.
The engine does crank at a good rate. How do you check the glow plugs are getting power? Can you tell me where to find and check the stop solenoid? Thanks