Geez, old man here trying to help my son. Here's the situation;
1980 F150 351 automatic 4x4 rarely used, dump runs etc.
A few weeks ago, truck wouldn't start and no lights etc. New battery installed, new cables but used old ground cable piece to ground from frame to engine. Cleaned both thoroughly before attaching. Still nada. New solenoid....almost started and starter wouldn't stop turning.. love those Chinese parts! Purchased another solenoid and all is well! A few days later, son needs to use truck..started fine and he drove it roughly 50 miles. Got home, parked it. Today, A few days later, he needed it to run a couple errands. No start! Nothing. He figured it was the starter so he purchased another. We put that on this evening but still no start. New battery is strong. However, loud clicking from solenoid with key turn. Tried to jump across terminals....sparks but no starter activation. I'm baffled. Any of you have any thoughts on potential problem?

 

That's weird, could be the solenoid is stuck and won't function even if you jump the terminals. Parts just aren't made like they used to be, maybe try tapping it a few times with a hammer, ya never know. No sense spending more money if it turns out to be something simple, though you may end up replacing the solenoid anyway if it continues to be an issue.

 

check all the grounds esp. the battery to block