Was your generator running? It comes of one the 2 tanks
1) Genset fuel draw
2) Filter restrictions
3) Fuel Vent/line restrictions
4) Fuel return line restriction
5) Operating torque or RPM discrepancy
6) Prop discrepancy
7) Heater System (Diesel)
8) Fuel leak
9) Fuel theft
10) Restricted crossover line
11) Fuel Manifold settings/restriction
12) Non matched injectors.