1983 F250 will not start?

You say you have spark so I can't see it being coil or ignition module. Have you removed and replaced plug wires? Perhapes you have the firing order wrong? You tried the shot of gas down the carb trick? Maybe your starter is fried, Ford starters have a bad habit of getting to the point where they will still crank the motor but take to much power away from the ignition for the motor to start, this would explain why it sometimes didn't start before. Also try replacing cap and rotor, maybe corrision in the cap is making bad spark, did you check spark from spark plug or coil? Just pull plug wires off and one at a time stick a drill bit the right size in it and then hold it up to a ground and see if it arcs. Could be dirty fuel and or screwed carb too but if so then it should at least fire on a shot of gas down the thoat of the carb.

Wiring the fuel pump to the ignition wire on the relay will only energize the pump while cranking the engine.

Fuel filter could be stopped up , the coil could be bad, There could be a number of things, air filter could be dirty, Make sure you have good fire good gas and a clean filter , If it cranks its not the battery or starter, good luck hope this helps.

Umm check the spark plugs, battery, and starter.

What kind of engine?

If it's a 351 W, it might have jumped time, meaning the timing chain

my dad had a similar problem with his 84 f150, turns out it had jumped time. It wasn't alot of fun to fix but we got it. good luck to you.