Eheim hobby pump

[sytauro]

I have an Eheim 1048 Hobby Pump and I've been trying to set up a closed loop through an Aquamedic Titan minicooler and a SCWD to 2 spraybars.
I cannot get the pump to prime so I can't get the flow started.
Is there a simple way to prime these pumps or is mine faulty? I tested it in a bucket of water on its own and it only worked intermittently, and not with the kind of flow rates I expected.
Can these pumps suck as opposed to only being able to blow with any power?

 

[Salt Freak]

maybe if you can get water sucked into the line were the pump is or get the air out of the pumps line.

 

[TexasPadreSurfer]

you may be having problems with whats called vapor locking this can be fixed by filling the lines the chiller and the pump with water before starting the pump, be shure there is no air trapped in the system. you can put a ball valve at the end of the line just before the scwd. start the pump and close this valve about half way,
NOT ALL THE WAY OR YOULL BURN UP YOUR PUMP OR BURST A PIPE OR HOSE
by doing this it keeps the pump from spitting out more water than it can suck in, do this untill you can see some water pour out one or both of the spray bars, then open the valve and see if it can pick up on its own, if this dosent work maybee the pump has somthing wrong, listen for wierd noises, i would take the pump apart and see if the manurfacturer did something wrong. i remember getting a pump with the impeller put on backwards it doesent matter on some pumps but most pumps cant run like that. also remember that the max head on that pump is 5 feet make sure the line does not get higher than 5 feet