1988 E350 fuel pump cut out

The high pressure fuel pump on my E350 pumps for about 3 seconds after the key is turned and then cuts out. I can bypass it directly and the vehicle runs fine. I have changed the fuel pump relay and EEC relay. When the key is turned I can hear the EEC relay click and then immediately after the fuel pump relay clicks and the fuel pump stops running. Has anyone had any problems with new relays being defective?

Thanks in advance

Phil :screwy: