The water level in the reservoir (8m) is higher than the elevation in J-3 (5m). and keep in mind the boundary condition where this system is dead end (is considered as closed system).
I have seen your demand is 60 L/s and the pump curve you are using it does not suite your model (it very big pump), so what are you trying to achieve from the model? in such models you do not need to worry about the curve, the most important is the operating point and the pressure in addition to the correct selection of the pump.
I hope that helps you.