Heat coals or gas grill for direct heat. Cut four 18x12-inch pieces of heavy-duty foil. Cut each squash lengthwise in half; remove seeds. Place squash half, cut side up, on each piece of foil. Sprinkle with salt.
In small bowl, mix butter, orange peel and 2 tablespoons of the maple syrup. Brush over squash halves. Fold foil over squash so edges meet. Seal edges, making tight 1/2-inch fold; fold again. Allow space on sides for circulation and expansion.
Cover and grill packets over medium-low heat 50 to 60 minutes, rotating packets 1/2 turn after 25 minutes, until squash is tender. Place packets on plates. Cut large X across top of each packet; fold back foil. Sprinkle pecans over squash; drizzle with remaining 2 tablespoons maple syrup.