Water Pump Issue

I live in Alaska and bought a used 2017 R pod 180 this winter at five below zero. Took it home and put it in a heated garage. Now above freezing, I hooked up to House power and water and flushed out the plumbing. Now I have filled the freshwater tank and turn on the pump which runs continuously, but does not prime. If I fill the pipes, it does seem to pump that water out with good pressure. I searched online for a good maintenance/repair manual and came up empty-handed. Before I start tearing things apart, is there a good source on how to troubleshoot the water pump? this is the first piece of equipment. I’ve owned in the last 20 years that did not have a huge amount of detailed equipment information online. trans transplanted myself from Indiana and am very embarrassed by my Hoosier engineers

+1 as to what Jato wrote. Now, to preempt the question, there are three valves in addition for the water heater. One on the line connecting to the top, one on the line connecting to the bottom, and a third bridging the top and bottom lines. If it was winterized, the top and bottom valves are shut and the bridging valve is open. Shut the bridging valve and open the top and bottom water heater valves and then you can flush the water heater tank also.

Here is a forum hint for you. If you find you posted something, you can delete it as long as nobody has replied to it. If someone has, it locks it so you can't delete it. You could always request a forum admin to delete the extra posts though. If the option to delete isn't under Post Options, look in the header under Topic Options.