As Hill described, there should be a lever beside the right side of the seat for raise, hold and lowering the 3PH. If yours is like mine, there is a black plastic knob in front of the seat. That is the speed regulating valve to the 3PH cylinder. On mine, this valve does double duty. If closed partially, it controls the lowering speed of the 3PH when a heavy impliment is attached. If it is closed down all the way, your 3PH will not move(up or down). When closed all the way this blocks the fluid from the 3PH lift cylinder completely and sends it all to the right rear quick connect fitting. If your 3PH is not working, make sure this valve is open/fully counterclockwise.
The two ports you mentioned are Jinma's version of rear remotes. The one on the right side of the tractor, if you follow it's pipe back, connects to the bottom of the 3PH control valve block. That is the supply line. That pipe/fitting is in parallel with the 3PH lift cylinder but it taps into the circuit before the speed reg valve. It was, I think originally intended to be used with a single acting dump bed trailer. If you screw down that speed reg valve all the way, all the 3PH fluid (entire system flow) goes to that rear QC when you lift the 3PH raise control. That is how you will get flow to your backhoe, so the 3PH control will have to be in the raise position and the speed reg valve fully closed to work the hoe. The port on the left side of the tractor should be a return and plummed back to the left side of the reservoir.
Another thing that will keep your 3PH from working is if you hook up your backhoe to those rear QC ports. Since the backhoe is open centered, if connected, when you try and raise the 3PH, the fluid will just flow thru the hoe instead of building pressure and lifting the 3PH.
So to summarize:
To use the 3PH, right rear QC will have to be disconnected from HOE or any other aux hydrulic equipment, and speed reg valve opened.
To use Hoe, speed reg valve closed, both rear QC's conected and 3PH lift control in the raise position to provide hyd flow to backhoe. If you forget to close the speed reg valve, as soon as the hoe comes under load, the 3PH will start to raise.
I timed my loader lift and based on the cylinder volumes on my loader, I got a little over 5GPM of flow on my pump at around 2000 engine RPM. They say that these hoes will run adequately on 4GPM, but I don't have much backhoe experience and have never tried it, so I am withholding judgment till I get mine. I will be interested in hearing how well yours works on the main system pump.
Here is a diagram of the 200 series hydraulics as I understand them. I drew in the aux and return QC fittings that yours has. Mine only had the supply port when I got it and I added the return myself. I would also highly reccomend you plumb in a pressure gage. My rear safety on the 3PH control valve was set too tight and would not relieve till 3000+ PSI. You want to make sure all the safeties are working correctly to prevent damage to the pump.
