also, the ecu must be seeing certain conditions, or it will not power the pump relay. if the engine dont start turning within a certain amount of time, it shuts down the pump, stuff like that. on some of the bmw's, there is a very popular relay that supplies the ecu with power. it failed all the time. if this relay is bad, nothing works. a lot of shops would call looking for the fuel pump relay. they would have jumped the pump, and it came on, so they would reason that it was the relay, because no power was getting to the pump. i would tell them to first check the dme(ecu) relay, and where it was in the fusebox. i would sell hundreds of dme relays, and i cant remember selling a fuel pump relay. heck, i sold hundreds of fuel pumps, too, but no relays. i am not saying the relay is good, just that there are a lot of mitigating circumstances.