My 1999 f150 wont start

Sounds like you have a bad alternator. Not recirculating juice back to the battery.

If the car turns over, its not the starter.

Try checking the car for trouble codes.

name the switch.
be exact.

but clean the battery lugs first.

Dirty connection at the battery post ?

I had a similar problem. The engine would turn over but not fire up. I was just about to spend a fortune on all the usual things, but decided to have the battery checkrd out first. Saved myself a ton of money. It had the volts but no amps. Put in new battery and It fired up right away.

Check the starter maybe needs to be replace and check the carbon of the starter.

I’m happy to assist further over the phone at https://www.6ya.com/expert/ramy_d9e7ebea3891f482

Incorrect, it's probably the battery. It has enough juice for the lights, but it needs lots of juice to start the engine. Get the battery checked at your local auto parts store, they do it for free.

bad starter

There are 3 fuel filters in he 528 and when you turn on the ignition, you should hear a buzz that means that the engine is being primed, if you don't, your pump hased gone, The Bms' have a system where the fuel is automatically drained back into the tank and automatically primed prior to starting the engine. This only takes miliseconds, but the primer part of the pump is not part of the mechanical pump so tahts' why it will start when pushed Let me know how you get on. Dave

I would check all of the connections to and from the alternator and starter, plus the grounds, they could be corroded or have weak connection, as far as no power going up a hill, check the map sensor