Betty Crocker says to cook a pork loin roast starting with the fat side up, then cover the grill to finish the process. Grilling takes anywhere from about an hour and a half to two hours to complete.
To cook the pork loin on the grill, start with garlic powder, onion powder, salt, poultry seasoning, chili powder and a center-cut pork loin roast that weighs about 3 pounds, Betty Crocker suggests. Heat the gas on the grill, or light the charcoals to begin an indirect-heat cook on the pork loin. Check the manufacturer instructions on the grill to make sure it is heated properly, Better Crocker explains.
Mix the garlic powder, onion powder, salt, poultry seasoning and chili powder together, and rub it into the pork loin. Keep the strings on the pork loin throughout the cooking process. Put the pork loin fat-side-up onto the grill and cover the grill. Let the pork loin cook for about an hour and a half.
Stick a meat thermometer into the thickest section, and make sure it reads at least 160 degrees. Taking the meat out prematurely increases your risk of food-borne illness, according to Foodsafety.gov. Once it hits this temperature, take the roast off the grill,and let it sit for 15 minutes before slicing it.