No power at all,no lights nothing is thier a relay?

What make , model year and engine size ? Reduced engine power usually means thier is a fault with the electronic throttle control an when thier is a problem it will disable traction control . This will turn on warning lights on the instrument cluster .

What do you mean nothing else works ? interior lights , radio instrument cluster lights etc. The alarm light flashes while truck is running ? Let's be a little bit more specific if you can !

The accessory delay relay supplies power (B+) to the driver master window switch . This relay is located in the central junction box ,under dash panel right side . An this powers the windows , the instrument cluster energizes the relay .
Interior Illumination is controlled by same relay .

If it has automatic lights find the photo cell that tells the controller when it's day light or nite. check it to make sure its able to see the light. If its ok it will be the controller. A service manual will help you fine thier locations which you might find at your local libary. If thier manual lights it the light switch I have had this problem on older trucks before.

Does it have spark ? engine compression ? Stuck open egr valve ?

Any codes stored in the PCM ? Is thier a security light lit on the insturment cluster . When you turn the key on , not start ,listen at the fuel filler neck with the gas cap removed > The PCM will energize the fuel pump for two seconds to prim the system . Can you hear the pump run . Turn it on an off a couple of times to make sure ! The best way would be to hook up a fuel pressure gauge . It sounds to me like your too fix on the fuel pump . When cranking the engine ,if the PCM doesn't see a input from the crankshaft position sensor it won't energize the fuel pump relay . If you want to fix your vehicle i suggest you learn how , an don't guess an just replace parts .
GM Fuel Pump Relay Testing
test the fuel pump electrical circuit

connection problem, somewhere. check battery cables-both, and connection at starter, and the battery ground on the body. May need to remove the conn.'s, clean off corrosion and re-tighten. If that doesn't fix, then start at the power distribution center under hood (probably near battery) and check your main power relays and/or circuit breakers. Hope this helps.

sounds like a blown fuse look at the connections at the starter relay that the battery cable connects to these wires the connect to the bolt on the relay that the battery cable conects to are fuseable links and you describe one of them as blown. You need to look for power with a test light to find the power and the ightion switch is a high failure rate part on this car and they were involved in a recall many years ago. thier so old now as you just chage them as Ford doesn't houner the recall any more the main relays also rust out at their connectors and the relays themselfs go bad too.

Hello tdyre13
The ECM relay is located in the power distribution ctr. under the hood at the right rear of the engine
compartment. Hope this helps.

nothing as no lights radiocheck ignition switch or nothing as in starter check relay and power at solenoid on starter when switch is in start position no power check relay have power replace starter

If you have just one thing that doesn't work you can also bypass it using a relay.

The headlights have 2 fuses. One is a main power feed under the hood in the distrabution box and the other is under the dashboard. Check the fuses and then check for power at the switch. If you have power at the switch then its not a fuse its the switch and the trailer you had connected most likely shorted and back fed into the parking and dash light circuit. Those circuits also run from the light switch.