Can my generator power my deep well water pump?
I had the very same question when I sized my generator to run my well-pump during power outages.  I purchased a clamp meter for under $100 and tested the pump on household current.  I simply attached the meter to the hot line and then turned on the pump.  My pump is 220 volt with two hot wires so I had to multiply the results by 2.  Unfortunately, I have moved-on from that home and don't remember how much power mine needed, but it was well under the 5500 watt stated capacity of my genset.

Also, it is important to note the starting current or use the "hold" feature on the clamp meter so you know the starting requirements and the running requirements.