The starting current of general electrical equipment is about 3 times the rated current. A 9.2 KW water pump needs a generator that actually generates 27/28 KW to start easily, otherwise the generator will be overloaded when starting, and. the engine will emit black smoke, etc.
Generally, the power coefficient of a diesel generator set is 0.8 (this is not necessarily true). If it is 0.8, a 100 kW diesel generator can actually generate 80 kW, and a 9.2 kW water pump needs a motor. 40KW diesel generator to drive it.
So the 20 kW diesel generator cannot drive the 9.2 kW water pump, mainly because of its difficult start.