If there are no leaks, the master cylinder is the most likely cause Although it is rare to have happen, the plungers in the master cylinder must be allowing fluid to bypass. The ABS won't cause the pedal to hit the floor.
Here is a link you may find of interest:
If you decide to replace the master cylinder, here are the directions. The attached pics correlate with the directions.
2013 Kia Truck Sorento 2WD L4-2.4L VIN 1 (MPI)
Vehicle Brakes and Traction Control Hydraulic System Brake Master Cylinder Service and Repair Removal and Replacement Repair Procedures
1. Remove the air cleaner assembly (A).
2. Disconnect the brake fluid level switch connector (B) from the reservoir.
3. Remove the brake fluid from the master cylinder reservoir with a syringe.
- Do not spill brake fluid on the vehicle, it may damage the paint; if brake fluid does contact the paint, wash it off immediately with water.
4. Disconnect the brake tube (C) from the master cylinder by loosening the tube flare nut.
ESC : 18.6 - 22.6N.m (1.9 - 2.3kgf.m, 13.7 - 16.6lb-ft)
5. Remove the master cylinder (B) from the brake booster after loosening the mounting nuts (C).
12.7 - 16.7N.m (1.3 - 1.7kgf.m, 9.4 - 12.3lb-ft)
1. Installation is the reverse of removal.
2. After installation, bleed the brake system.
Let me know if this helps.
Images (Click to enlarge)
Monday, January 27th, 2020 AT 7:16 PM