Return pump priming needed?

[Eb0la11]

Hey guys, ok got my leaks all worked out for the most part and the drain works etc... So naturally the next step was to fire up the return pump.

I have a submersible return pump that fits in a chamber in my sump. Its completely submerged. Its an ecoplus 1584 pump. Brand new. It works, I tested it outside just submerged in a bucket and it shot water 3-4 feet high.

So, my problem is that when I have it hooked up to my four 1/2" return lines through a 3/4" manifold it wont push water through.

I have a check valve installed about 4 inches up the line from the pump that is not backwards and for some reason my pump isnt feeding water through my returns. Ive closed off 3 of the 4 to see if it could pump through just one and no luck there either.

Anyone know what might be my problem? Ive got the return lines full of water to "prime" them and this has caused the check valve to close the other direction, but the pump should be powerful to push it open again and begin flow, no? Im confused.