What Titan Tech Support said"
"Yes 66 amps is too high for a 3,000 watt inverter, even though it is only for 300 to 400 milliseconds. The inverter probably never gets the pump going, because it can't handle the startup load. If the continuous load is only 1500 watts, it would probably run it if it could get it started.
The soft start may reduce the initial load, and get the pump going, however a 3600 watt inverter is larger than a 3,000 watt inverter. So I am not sure if that pump would work with the Titan either.
We really don't recommend well pumps with the Titan, since we have never tested one that worked. You also have to be careful with AC units. The Titan works with most small ones, but larger ones it will not work with. But large inductive loads like well pumps, and AC units are hard for inverters to run. This is one of the reasons we are working on our 2.0, which will allow you to connect two units together to produce 6,000 watts (120 or 240V). We have tested this on well pumps, and it has worked great."