Hi,
it's not a PP issue, ever since season 3 you got gear check (armor and weapon condition) for caravans, that means if you have gear that is damaged too much, caravan masters won't accept you. I don't remember the exact condition of gear that makes you pass the gear check, but making sure it's above 50% should make joining caravans possible.
Also, you can equip weapons such as knives etc that have no deterioration, that way you will always pass the weapon condition check, and after that equip the weapon you will use in the run.