Originally posted by pfgjerpe
Thank you very much for your answer.
I will try the things that you mentioned in your mail, as soon as I can find the fuel pressure regulator.
Thanks again !
Just thought that I should post the solution in case other people should encounter the problem :
After a while the engine refused to start by starter motor even when cold, however it still started easily when pushed downhill (hot or cold)
The solution was that overload voltage releay was busted. Even though this releay has a fuse. In addition they changed the fuel filter. Now the motor starts every time very easy.
Regards to everyone who helped me