Well, could be a few issues. First, make sure your fresh water city inlet doesn't have a defective valve. Do you have a basement full of water? I had one go bad on my Jayco and I couldn't figure out why the pump was running & running. My wife yelled that water was spraying out the city inlet. That was a simple fix but annoying.
Second, ensure that your plug is installed in the HW heater. Then make sure the by-pass is not engaged for the HW heater OR the antifreeze pump line. Also, make sure your fresh water tank is half full and that the plug in the bottom is installed (I've been there). Fill the tank as mentioned, close all faucets and outside shower to the OFF position. Open only a single faucet, both hot/cold on the faucet furthest from your tank/pump. Turn the pump ON, this will bleed air, fill your HW tank (this can take a bit) and will circulate water through the system.
If this doesn't work the pump itself may not have been winterized correctly, there is a check valve in the pump. Is this defective?
2013 Jayco Eagle 334RBTS
Crossroads Forum Lurker