Pump priming is simple. As long as there is constant liquid reaching the pump, it will prime and pump. The less air in the suction hoses the better the pump will prime and work.
When transferring sealer from drums to the main spray system tank make sure the transfer kit hose is completely full of water. Connect the barrel pipe to the transfer kit and then the other end of the transfer kit to the suction port of the pump and make sure the transfer kit hose remains full of water. Put the barrel pipe into the sealer drum. Make sure the ball valve handles are in transfer mode. Start your motor and begin your transfer.
The pump only needs to be primed the first time you use it or if you haven't used your pump for longer than 24 hours. Use 1 gallon of water in the pump through the pump orifice allows the machine to immediately push that liquid through, creating enough force to start pulling sealer from the tank.
If air is hitting your pump at anytime it will lose prime and the chances of burning up your seals are high. Make sure water or sealer is always reaching your pump.
If the pump is leaking between the engine and the motor, it's usually caused when the pump overheats, due to running the pump dry. The main master seal heats up and shrivels up, creating small cracks. Always make sure you run some kind of liquid in your pump, whether it be sealer or water during priming.