Easy Grilled Tri -Tip

4 lb Tri-Tip

1/2 cup lemon juice

1/2 cup veg oil

1/4 cup brown sugar

1/4 cup soy sauce

1/4 cup coarsely ground black pepper

1/4 cup seasoning salt

1/4 cup minced garlic

1/4 cup dehydrated onions

1/2 tsp. white pepper