Sure, vapor lock occurs when the gasoline gets sufficiently hot to go from a liquid to a gaseous state(vapor) The temp this occurs is a function of the pressure the fuel is under at the time. if it's low (the pressure)or there's none, then it goes to vapor relatively easily. if there is pressure on the liquid, then the flash point (point where liquid changes state to gas) will be higher. The accumulator helps to keep static pressure maintained in the fuel system to prevent fuel pressure bleed down and ""vapor lock"". If you can imagine a huge bubble in the fuel pump or one of the other fuel system components, you can then probably imagine why the car gets fuel starved. it's kinda like an air embolism for automobiles. Hope this helps.
1987 BMW 325