I had manual ball valves (photo 3) on the drain hose for both rear tanks to allow me to fill my 750's all the way. I kept them closed at all times until it was time to drain my sacks. It worked great thanks to Eds advice, but I wanted to make it a hands free operation. So I decided to change out the manual valves with electronic valves (photo 2), connecting them to my ballast rocker switches so that I never have to turn a valve again.
Cost: Approx $80
2 12v electronic brass valves 3/4", set at NORMALLY CLOSED (they only open when they have power to them)......delivered = $68 (photo 1)
1 50' section of 16g "lamp cord", low voltage wiring, at home depot = $8 (photo 6)
4 female electric connectors 12-10 guage = $4 (photo 4)
Everything else I already had. If your replacing manual valves, it is a lot faster, if starting from scratch, you will need more materials.
1. Replace/install valves anywhere on drain hose (preferably behind that carpeted cover with the LED on it in each locker)
2. Connect lamp cord to the electronic pumps (mine used wire butt connections x2 each pump)
3. Run lamp cord across back of seats to starboard side locker, attach cords to the electrical harness that runs up to the dash. You can fish the wires to the front of the boat easily by using the access hole over the cup holder/speaker pocket, then again in the ipod cubby under the throttle. Finally there is a real big hole in the fiberglass behind the dash where all the wiring from the whole boat seem to exit.
4. Locate ballast switch 8 pin connector housings from behind the dash (photo 5). Rear-Left ballast connector housing is the 3rd from the right. Rear-Right ballast connector housing is the 4th from the right (in the picture, this housing has been removed so all you can see is the back of the rocker switch and its 7 flat pin male connectors.)
5. Remove one ballast connector by pinching the housing with a finger on top and your thumb on the bottom. You will need to squeeze hard to release the clip on the thumb side of the housing. The housing has 8 slots (photo 9). Top right= 2 black wires, grounds for both fill and empty pumps. Left top = 1 brown wire, the power wire to the EMPTY pump. Below that is 1 red/orange power wire. Bottom left = 1 brown wire, the power wire to the FILL pump.
* same for the rear-left connection except my power wire was green. (I used a voltmeter to find the hot wire and pump power wires)
6. From the front of the housing, slide a very thin flat head screwdriver or something similar in between the FLAT SIDE of metal connector and the plastic housing. This will push the metal tab from the connector flat so that you can pull the connector out the back of the housing. (Look at PHOTO 4, if you look closely at the top connector, you may see the flat side of the connector is up and there is a small tab bent up.) Pull out the ground connector with the 2 ground wires, and the top connector with the brown wire.
7. Cut and strip these 3 wires. Strip your valve wires. Take one female flat connector and strip the plastic insulation off (photo 4 you will see 3 female connectors, top is original, middle is new connector, bottom is a new connector with insulation stripped). Put 2 pump grounds and 1 valve wire into connector and pinch it so its secure (photo 7). Do this with the brown "drain"pump wire and the other valve wire.
8. Put connectors back into the housing as you found them. (photo 11)
9. Connect housing back onto the rocker pins, it will 'click' into place. The 2 new connectors in the housing DO NOT HAVE the metal tab that holds the connector in, so you WILL HAVE TO push the connectors on all the way from the back of the housing. Just push them in by grabbing the wires.
10. Now toggle your rocker to "drain" or "empty" and you should hear a "pop" sound of the solenoid opening the valve AND your drain pump turning. If not, make sure your new connections are on correctly. check to see that your "fill" pump turns on as well.
11. Repeat this with the other side, then use zip ties to organize your 4 new wires.
12. go shred....