| I am not familiar with that type of pump, and do not understand some of the details. I have a lot of experience with different pumps, and maybe with my general experience we can figure it out.
Most water pumps do not pump air very well. Many must be filled with water from the intake to the pump. It will be easier if the pump has a foot valve at the end of the pipe down in the lake. Then if it is a centrifugal pump without any other check valves, you simply fill the system by adding water to the outlet and turn the pump on. Other systems are more difficult.
It sounds like you need to open both valves, and run water in the first one until the system if full. Then close it and turn the pump on. Leave the second open unless water runs out it while filling the system. If you have to close it to fill the system, open it immediately after turning the pump on. If you have any leaks air can be drawn in, the pump will draw air instead of water.
I once managed a factory where we had a 6,000 gallon water tank buried under the floor, and the pump a 1 1/2' above the floor. As long as there was any water in the tank at all, and the pump was running, it pumped fine. If the system lost any water, and we shut the pump off, we couldn't restart the pump until the the tank was full and the system up the the 1 1/2' above the floor. We lost large amounts of production time waiting for the tank to refill. I eventually fixed the system so we lost less water, and air didn't get carried down to the tank. |