In a small mixing bowl combine the chili powder, garlic powder, onion powder, smoked paprika, ground cumin, and salt.
Sprinkle the pork rub over the pork loin and rub it in with your hands.
Pour 1 cup sugar-free rootbeer in the bottom of the instant pot. Place the pork loin in the pot. Cover with the lid and make sure the release valve is locked. Set the manual setting on high for 60 minutes.
When the Instant Pot beeps, allow it to do a natural release for 20 minutes.
Unlock the valve and carefully transfer the pork from the Instant Pot to a cutting board.
Pull the pork into pieces using two forks. Place the pulled pork in a storage container and cover with ½-3/4 cups of the cooking liquid. Toss to coat.