Hydraulic Power System in Simulink

The aim of this system is for the pump to power the motor, it also pressurises the accumulator, when the accumulator has been fully charged it will release and give the motor extra power. The system right now works partially but i would expect to see the the flywheel spin at a constant speed and the accelerate as the accumulator is released, also i would expect to see the accumulators pressure to rise gradually and the drop as its released and then start to rise again. Any help or pointers are very much appreciated, Thank you in advance