im building a rally spec wrx sti, and having just fitted everything, it too wont fire up, it will turn over etc , like yours, after checking we have found the immobiliser is missing from the loom, so the key and the ecu wont talk too each other. the immobiliser it seems controls the injectors, so they shut down.
to cure it its going to Geoff jones motorsport in wales to have a motec ecu fitted with anti lag.
stu