Why are you turning off the solenoid? If you have it turned off it can't provide
oil when its needed at low pressure, except for pre oiling at start up and that's assuming its had a chance to fill with
oil. You probably should only have about 5psi maximum when the system is purged of
oil. Open the solenoid and apply say 60 psi and wait while the oil is purged from the accusump repeat a few times until all the oil has been purged from the accusump (it may have become hydraulically locked, ie filled with oil with no air space). After purging the accusump of oil turn off the solenoid and bleed the air valve until you have about 5psi on the accusump guage. Start the motor then turn on the solenoid and run for a while till the accusump fills with oil and your pressure guage on the accusump should display your engine oil pressure. Turn the solenoid off before turning the engine off. Without starting the motor check over the next few days to make sure the accusump maintains a constant pressure because any leak and loss of pressure will cause you issues.