Just the opposite, George. Higher fuel pressure raises the temperature (amount of heat) required to turn the fuel into vapor. So higher fuel pressures tend to lower the likely hood of vapor lock – however, if you raise the fuel temperature high enough, you can probably turn it into vapor regardless of the pressure. So higher fuel pressure tends to reduce the likelihood of vapor lock but can not absolutely prevent it – expose your fuel to sufficient heat and you can probably achieve vapor lock at any pressure.

The newer returnless systems monitor the temperature of the fuel as well as the pressure. I would presume (but don’t know for certain) that sensing higher fuel temps would cause the control system to increase the pressure. It may be that the basic pressure (around 42 psi) is sufficient to control vapor lock under the anticipated operating temperatures. I would have to figure out what it would take to heat fuel to its vapor point at 42 psi.