Which relay are you referring to when you say ECM?
Are you talking about the one in the manual's diagrams labeled "PCM Main Relay" in the fuse/relay box in the engine compartment?
If not, that's one possible culprit. Another would be the 40Amp EB18 "PCM" fuse in the same fuse/relay box.
The PCM relay would be affecting the powertrain control module, the fuel pump relay, and the fuel injectors.