I have a 2000 F150, 5.4L with starting issues. If I turn the key to 'start', there is no click or anything, and the radio goes dead and won't come back on. BUT, if I just turn the key to the 'run' position, I can start the truck by jumping the posts on the solenoid on the firewall. It starts right up when I do this, no starter drag or anything, just turns over and fires up. Someone had mentioned that it was an alternator problem, but if I disconnect the alternator while the engine is running, it never skips a beat and keeps running. I had a loose post on the battery so I replaced the battery, but it hasn't made a difference. I'm guessing maybe the ignition switch?

 

The solenoid on the firewall has went bad, min did this a couple of months back. Quick and cheap fix.