Prepare medium-hot banked fire in kettle-style grill. Season pork roast with salt and pepper. Grill over indirect heat, not directly over fire, in covered grill for 1 1/2-2 hours (about 18-20 minutes per pound). Meanwhile, stir together barbecue sauce, jelly and chili powder. The last 30 minutes, start basting with sauce mixture every 5-10 minutes until internal temperature of roast, measured with a meat thermometer, reads 150-155 degrees F. Remove roast from grill and let rest 5-10 minutes before slicing to serve.