Step 3: Grill the Pork Tenderloin. For the quickest method of grilling, place the pork tenderloin on the grill between burners if using a gas grill, or over the hottest part of the coals if using a charcoal grill. Replace the cover, and cook for 1 to 2 minutes or until grill marks appear. Flip, and continue cooking, covered, 1 to 2 minutes. Repeat this process several times (pork tenderloin typically takes about 15 to 20 minutes to grill), replacing the cover between flips, until meat is cooked through. The meat will feel firm yet springy when poked once it is finished cooking.