Hyundai H1 Starex 2.5 TD Start failure

Hello I have a problem with my Hyundai H1 Starex 2.5TD 80CV of the year 99 ....

in cold it starts perfectly, but by doing as more than 60km when turning it off and when it turns it on again, it no longer starts me, the starter engine works perfectly but does something as well as if it does not enter diesel. We have changed the impulse collector and the unemployment valve, but still fails, would anyone know what can I do the most? THANK YOU AND GREETING COMPANIONS !!