The real problem with the Accusump control system is the pressure sensor. It tends to overheat and fail, so the valve stays closed. There are several threads on LT documenting repeated failures of this sensor. Support from Canton has been nonexistent as far as I can tell.
You can check your sensor by applying 12V to the electric valve. If it dumps the oil, the valve is okay. Then check the wiring. If the circuits are good, the sensor is the problem.
I addressed this issue by removing the pressure sensor. I wired a cockpit-mounted toggle switch to control the electric valve. This allows the unit to operate as a full-time hydraulic accumulator rather than just an emergency oil supply. I turn the valve on when I start a track session, and turn it off during pit in. This is basically how the system works when installed with the cable-operated mechanical valve. I have to remember to turn it on and off, but I think that's a good tradeoff for greatly improved reliability.
In theory, there is no difference between Theory and Practice. In practice, there is. - Y. Berra