No fuel to the rail
 

I'm a new '96 318ti owner and not familiar with the complete fuel system operation. Problem: no fuel pressure to shrader valve. I've changed the fuel pump fuse and relay, the fuel filter and the fuel pump. No help. With Key to start I get 10.5 volts to fuel pump connector and pump spins for 1/2 a second but no pressure. If I run 12volts straight back to the pump it spins up , I get fuel pressure and the car starts and runs fine. But when I plug the connector back in it's a no go. No fault codes on OBD2. Any Ideas?