1991 ford f250 batter and truck keep dying while running

The alternator is not working. When running, a voltmeter on the battery should be at least 13.5 volts, showing the alternator is working and the battery is being recharged. You have a charging system malfunction. check the connections between the battery and alternator. Check battery ground, engine grounds, and engine to body strap ground.

replace the ignition switch or, run a new hot wire from the ignition switch run side to your fuel pump positive terminal

Check and clean and tighten all battery, starter, and alternator connections. Also the battery and engine to chassis grounds. Did you have the battery " load tested" as a good test requires?
Take the battery out and have it charged up. If the alternator is good, you should not have any more problems. But if you need a jump after a few days to start it, then either the alternator or the battery is just not up to par. Have the alternator tested while on the car and running.
Good luck.

I think you have a couple of problems going on here. First a solenoid would not cause the engine to lose power until it dies. This problem will probably be an alternator going bad, bad battery, or bad battery connections (check ground wires on engine, body, and battery then check positive wires on battery and to power distribution block). These related issues can be the root cause to solve the starting issue, which I will discuss now.
I recently repaired a 94 F-150 that would not even click when trying to start it. It was the push on connector to the solenoid on passenger inner fender well. I have also seen where this solenoid loses its ground (corrosion between screws and fender well). The 94 had two solenoids, one on the fender and one on the starter. To see if the solenoid valve is good, you can use a jumper wire from the hot side of the solenoid to the small terminal stud. If it clicks it should be okay and the ground okay. Be sure to have the vehicle in park or neutral with the parking brake on before doing this, because you are bypassing safeties.

that is the quickest way to check the alternator leave it iddling and disconect the earth cable if it stays running its ok or my own way would be to use a volt meter and if it has about 13 volts or there abouts its ok and that would suggest a faulty battery or somethung draining the current wken its not running

chec the volts regulator. its very common in ford trucks

turn every thing off and remove neg. batter cable if u get a spark then u have a short some place that is pulling elect when car is off

You need to have the alternator re-checked and be sure the wiring is clean & correct. If an alternator is working properly & wiring is correct, those batteries should be charging as you drive.

It appears that the alternator is still not charging the battery.Charge the battery up,and refire the truck.Check voltage with a voltmeter,directly off the back of the alternator.Most all alternators of your year model have the voltage regulator built into the alternator.If the alternator isn't producing any voltage,then it is bad,even if it is new.I have had defective new parts before.

bad battery module for the light or a dieing cell in battery

batterys can be tested and wont show a dead cell at all but you will be told that the battery good
most batterys are refurbished batterys sometimes getting the luck of a good battery is 50/50 chance

heres a way to test the battery and alternator at the same time
start vehicle
disconnect battery positive post
if vehicle dies the alternator is at fault if vehicle doesnt die its the batterys life dead cell