Pat the roast dry all over using paper towels or a clean kitchen towel.

Place the roast in a deep aluminum baking pan.

Fill an injector with half of the beef marinade and inject it all over the roast, making injections about 1 square inch apart.

Pour the remaining marinade over the roast.

Cover the roast with foil and refrigerate it for at least 6 hours or overnight for the best result.

Preheat a smoker to 250°F.

Remove the roast from the pan and pat it dry all over with paper towels or a clean kitchen towel.

In a small bowl, combine salt, pepper, onion powder, and garlic powder.

Rub the spices all over the roast.

Place the roast back in the pan and transfer the pan to the smoker.

Cook the roast for 5 hours or until the internal temperature reaches 155°F on an instant-read thermometer inserted at the center of the roast.

Remove the roast from the smoker and transfer it to a clean aluminum baking pan.

Cover it with aluminum foil and wrap the pan in an insulated moving blanket.

Let the roast rest in a cool, dry place for 1 hour.

Unwrap the pan and transfer the roast to a cutting board, reserving any pan drippings.

In a medium saucepan over medium heat, bring the reserved pan juices to a simmer.

Simmer for about 5 minutes, stirring occasionally, until heated through but not boiling.

Pour the heated drippings over the roast, carve, and serve immediately.