Couple of issues I can suggest checking, went through some of this before myself.
First, can you check that the pump is working? If it is on drain can you hear it running? They are mounted back near the transom in the engine bay. If you can't hear it, switch should light to confirm power. If no power, then check the fuses and breakers.
If you know it's running and just not draining then it's likely losing prime, I have blown through my drain hose and kick started the process again but it's a pain.
From what I have learned the drain pumps are mounted in the engine simply to keep the install clean. The issue is with the drain hose length as the drain pumps are not self priming, they are an aerator style pump. The fix relocating the pumps to inside the locker and shortening the drain hose so the pump essentially is connected directly to the bag. You will have the bags quick release male fitting, 1 1/2" of drain hose then the pumps fitting and then connect to the pump. The pump will lay at the back of the locker and should work MUCH better now. You will not need to buy anything except a couple of hose clamps if you dont have any. Everything else you are reusing.
2007 Supra Launch 22SSV
(2) Wetsounds Rev 10's, (6) XS-650, (1) Syn 6, (1) Syn 4, (1) Kicker 10" Sub, WS-420SQ Full RGB LED on Wetsounds
(2) SeaBlaze 3 Blue Transom Lights
Supra Surf swim platform
NauticLogic GPS Speedwheel/Perfect Pass Interface
Wakemakers Ballast Upgrade, 3 Pump Fill, 3 Pump Drain