I'm not sure exactly what your issue is. Are you not getting water at all from the pump? Or just low flow? Or is the pump not working?
This could be a lot of different things from a faulty pump, kinked water lines, bad check valves, or the water system flush valves being in the wrong postition.
If you can give us some more details someone here may be able to better help you.
2011 Chevy Silverado Crew Cab 4X4
2009 210 WBS