Here's a Pipe Friction Loss Calculator to help you calculate pressure drop in fuel -oil piping.
Pipe Friction Loss Calculator
Tips:
Viscosity (cP) of #2 diesel fuel: ~3.5 Specific gravity of #2 diesel fuel: 0.85 Be sure to account for vertical head in your piping run: 1psi = 2.70 feet of #2 diesel fuel with specific gravity of 0.85.