Not to be nit-picky, but this is more of a thermodynamics question than a fluid dynamics question (you may want to re-post this in the Heat Transfer and Thermodynamics Engineering forum).
I believe to solve this problem, you need a tabulation of the properties of Diesel Fuel #2 in the compressed liquid state. This is probably not something you can find in the run-of-the-mill undergraduate thermo text-book (mine only has tables for water in compressed liquid state). Someone in the Heat Transfer and Thermodynamics Engineering forum may be able to direct you to tables or an equation.
Good luck,
Haf