Drive'n and i thought i ran out of gas /try to prym it

Could be crank shaft sensor.

When the Check Engine light flashes it means there is a significant emissions problem detected and it needs to be fixed very soon. Continuing to drive with this condition will destroy the catalytic converter. You may have gotten debris in one or more of the injectors when the gas got low.
The first thing to do is get the codes read and find out what the computer is reporting bad.

It may be the sending unit in the tank that needs replacing. Here's how you can check: Turn the key on and disconnect the sender unit at the gas tank. Ground the sender unit's wire with a jumper wire from the truck's harness to ground. Watch the gauge. If the gauge on the dash is good, grounding the sender wire will cause the gauge needle to react and should move to full. This would indicate a new sending unit is required. If the gauge doesn't move when the sender unit is grounded, the gauge is bad and needs replacing. Pull the instrument cluster out to replace the gas gauge. Likely any old ford gas gauge might work-back then, there were not so many production changes.

You have most likely sucked residue in the bottom of the fuel tank into your fuel filter, This can cause it to get blocked, Try fitting a replacement fuel filter as it's most likely it's never been changed anyway.

first replace the filter this is the least expensive repair..when u ran out of gas u may have sucked up (dirt) in the fuel tank.....if that doesnt work bring it to a service repair station an have a fuel pressure gauge hooked up to it....this willl tell u if the fuel pump is starting to fail...when u run low or out of gas the fuel pump can over heat an cause premature failure....u should never allow ur gas to go below a quarter of a tank since the fuel is what cools the fuel pump

fuel gauge has to be faulty the fuel gauge puts the low warning light on

R does mean reserve

Try changing the crank sensor or coilpack.

yes the most likly cause is that the fuel level sensor is faulty i would put a gas can in the back and go for a drive the a shop and have them check it. but i think if the truck wont take any more fuel it will be a faulty fuel level sensor.

Likely blew the fuel pump. I think it's in the tank. Check for dead short.