I need help finding why my ford f150 1989 truck won't start and my positive battery wire gets hot

I need help finding why my ford f150 1989 truck won't start and my positive battery wire gets hot - 1

Clean the terminals (both ends of each until both contact points are shiny) and try again. If nothing changes clean starter power connections (both ends), if still no improvement replace the starter.

The starter is bad.

Like "spacemissing" has already said, your problem is either the starter is locked up or the starter solenoid is shorted.

Did you give us too little information on the problem because you want a lousy answer? Is it turning over but not starting, not turning over, clicking?

Getting hot is a result of high power flowing through the wire. Often denoting a 'short' circuit. Car fires can start this way. As for non starting. We have not mentioned if it cranks? Assuming not… Then we have a solenoid fault. Exchange starter and solenoid likely here.

You're cranking the motor too long if the cable is getting hot.
There are so many reasons a motor may not start you need a mechanic.

Any of the other answers might be right, but my guess is that the connection of the positive wire to the battery is dirty. If you have not done so already, clean the post and the connector. There's a special wire-brush tool made for that job, and you should own one.