Additionally if your engine is cowled an arguably more reliable method with none of the problems of a fueling valve that costs nothing is to just run the feed line out a small hole in the cowl and right back in half an inch away on its way to the carburator. cut the little loop and insert a short piece of tube and fuel from there. If the muffler pressure line is also inaccessible do the same for it right under the feed line.

John