Just had a fuel pump problem during a recent trip to Bend Ore. Was really hot and the engine sputtered and then quit. First thing that came to mind was a vapor lock. No fuel in the carbs. Turned out that the fairly new pump was not pumping fuel due to the pivot pin of the pump lever had moved out and the level fell off. Luckily I was able to put it back together and it then ran fine.
Starting fluid is a very dangerous product to use on any engine. Popular to use on diesel engines. Overuse can take out the rings and damage the cylinder walls. In my shops I would not allow its use. If it wont run on its required fuel, fix the problem, do not create more.