03 plate 2.4 diesel 125ps non starter

[hct235]

03 plate 2.4 diesel 125ps non starter
engine turns over ok, heat light goes out, no warning light flashing,
turns over chugs as if going to start or try to fire but doesnt was ok when i parked it up the night before.
when i started yesterday morning there was a burning smell and smoke came in cab, but started ok. ran & started ok every time during the day.
any ideas?
regards karen