As danny says more likely to be a dodgy connection, probe for power at the ecu(from the relay) when you turn the iggy on, if there is a dodgy connection here that could/would stop the ecu/fuel pump/prime.
It's more likely to be something you've disturbed though in the engine bay, but make sure the basics are there first, main power control relay.
What alarm/immoby is it btw ?
tabetha