what would cause coolant not to come out motor into upper radiator hose
Just put new water pump on
The car needs to be running to get it up to temperature first, then the thermostat can open and the coolant can flow through the upper hose into the radiator.
And if the engine is already running which I'm guessing it is, that's a sign of air trapped in the system. There's a bleeder valve near the thermostat that is used to let out the air. I've also read that it helps to have the car parked facing uphill while filling and bleeding the system. Getting the air out does seem to be a bit tricky on these engines, but its imperative that you do or you will overheat and damage other things.
Looking for a Used Grand Prix in your area?
CarGurus has 3,715 nationwide Grand Prix listings starting at $1,100.
Search Pontiac Grand Prix Questions
Pontiac Grand Prix Experts