At witts end
 

I have a 99 ford F150. 5.4 v8.XLT. I started my truck in the morning it ran fine to the gas station. I shut it off, filled up the tank. And now it will not turn over. The Alternator is two years old. I have lights But no power. I am thinking maybe the starter but I am not sure. Any suggestions? Any help in this matter would be greatly Appreciated.

all the lights could be bright as they can be and still no start. because the starter draws way more power than all the lights put together. sometimes and this ain't always the case but you could have a battery cable that's corroded on the inside and never know it, and you didn't mention how old the battery is. welcome to the sight

Way back then,,,,,,,,,,,,,, that was one of the checks we used to do. With the headlights on watch the lights when you tried to start it. If it didn't do anything and the lights did not go dim it was a starting system problem. If they went dim either the starter was pulling too much , or the battery was too low, or the cables were suspect.
If there is no change in the headlights when attempting to start we looked for a wiring problem to the relay, the relay itself or the solenoid on the starter if it had one or the starter itself. I know Grindman was going to post this next, but he probably stopped for coffee.

Thank you for the input. I changed the battery cable today and that only made things worse. Now I have no dash lights or radio. Also the battery is two years old and had it tested at ford when they changed out a coil.

James, if you replaced the battery cable and didn't reconnect the other wires when you installed the new cable, that would explain the radio. another thing that Ford did that was pretty dang stupid on their part was to change the way the cables were routed and the way it operated and then they stopped making the extra parts so that when one goes to replace them one can't even buy the oem parts from ford