There should be a fuel pump test connector, 5.7L gas engine. Underhood, driverside, close to firewall and relay pack, red wire with connector, nothing plugged into it. If you use a jumper wire and run B+ to the connector, the pump should run. You don't have to use the key. Use an inline fuse on the jumper. If the pump won't run, check for voltage at the pump connector, gray wire, if no voltage, something wrong with wiring circuit.
The pcm sends voltage to the coil side if relay, in order to energize, green wire with white tracer. At initial prime, key on engine off, the pcm may energize the relay for couple second, then without rpm signal, engine cranking, the pcm won't energize the relay or injectors. But, with the o/p switch in the pump circuit, and the switch circuit is functional, the pump will run and make pressure, regardless of the relay.
Monday, September 14th, 2009 AT 11:35 AM