Ok, 2002 Buick LeSabre that died while driving and after replacing the fuel pump, it ran for a short time and died again. Put a second fuel pump it and getting no pressure at the fuel rail.

So we have narrowed down the issue to the fuel pump is not getting activated. It is a new pump and we had a mechanic feel it was the Ignition Control Unit not sending a signal to the pump. He opened the fuel pump relay and manually activated it and you could hear the pump starting up, so it is capable of functioning, but it is not getting activated for some reason. We replaced the ICU this morning, no change, still do not hear the pump activating. So we know we are getting power to the fuse box and relay under the back seat, however, the relay is not getting triggered (changed the relay to another one to see if the issue was the relay). So seeking other ideas as to what would be next to look at as to the problem?