2003 Sprinter don't start

[ktbstudio]

Hello

I had a problem, with a sprinter 211 cdi, it starts hard, cold or warm. I saw here a topic, with the same problem, and i changed the 2 o rigns on the pressure regulator. I remounted the regulator, for the first time, the engine starts normal and easy, then at the 2, and 3th start starts after a lot of cranking, and at the 4th time, don't starts.
Probably the pressure regulator is failed?

I mounted a pipe to the end of the regulator, where is the 2 o rings, but the regulator don't keeps the pressure. After 10 seconds the vacum pressure is 0.

Need to change the regulator?

Thanks.