“Fuel system cleaning” used to be a largely a do-it-yourself affair. You know the routine: Joe Vehicle Owner would buy a can of his favorite brand of spray carburetor cleaner, remove the air cleaner, spray the heck out of anything that looked like it had anything to do with carburetion, start the engine, then finish the treatment by spraying the remainder of the can down the carburetor throat while attempting to keep the engine running.