The U.S. EPA's publication "AP 42, Compilation of Air Pollutant Emission Factors", Chapter 7, Table 7.1-2 gives the following True Vapor Pressures for Kerosene (which is essentially #1 Diesel:
40 deg F = 0.0041 psia
60 deg F = 0.0085 psia
80 deg F = 0.015 psia
100 deg F = 0.029 psia
See if you can locate an MSDS sheet for the actual material in question- they quite often show that on there, and saves you wondering whether "essentially" is close enough.