[Tommy]

Doug,
There are two common vapor lock problems that I know of. One is when a hot car sits and fuel in the carburetor or fuel lines near the engine get hot enough to vaporize the fuel. The second is when fuel pausing in a pressure regulated electric fuel pump gets hot enough to vaporize causing the pump to cavitate and not pump fuel. This second case is where a pressure regulator and fuel return line downstream from the pump can help. It allows fuel passing through the pump to move through before heat from the pump can can cause it to vaporize. .... I suppose a fuel return line might help the first case also, but the return line would have to be closer to the carburetor than the site of the vapor lock.

I learned this when my electric fuel pump vapor locked on a hot day at the track. A separate pressure regulator and return line solved the problem.