I have no oil pressure in Ford Transit 2.5 Mot

Hello, can someone help me ??? Do not raise my ford trnasit pressure, we made a cmployed engine, the folk pump is new, if the oil filter lifts pressure without any problem, but I stop it and I start again I have no oil pressure ... the pressure regulating valve is new ... I have disarmed it about 20 times, and I have the same problem ... the oil shock that goes in the carter Help, I'm going to thank you for ...

Hello, I would like to know if you found the problem I have a transit in the same cituassion, thank you very much