Figured it out and feel pretty dumb. I relocated the city water connection to the back of the RV for ease of connecting and when I first changed the pump it was hooked up (but house hose off). Today I had unhooked the hose and it was spraying water back out my new hookup. I'm now assuming there must be an anti-backflow valve at the stock city water connection.
The odd thing is the old pump was doing the same thing long before I moved my city water hookup (this is why I swapped the pump). Anyway, all is well.... for now. Thanks for the replies everyone.