I tested this out in vanilla as a check, and I'm not 100% sure this is Fantario's fault...but it might be. In Fantario, if you place a burner inserter next to a burner building (i.e. both the inserter and building require fueling to operate), the inserter will fuel itself using the fuel reserves of the building...BUT if you place the inserter before the building has fuel, and it is LATER fueled, the inserter will not pick up any fuel. This may not be true of all burner buildings, but it is definitely true of the burner chemical plant and burner assembly machine. This behavior does not occur with boilers in vanilla nor with drills in either vanilla or the mod; in those cases, it does not matter when the fuel is added to the source building.
