Water Pump - Not working right - well sorta

Thanks all for your replies. Full fresh water tank, all faucets closed, no outside hand faucet, all valves set for camping and by-pass open to Hot water tank. Air leak sounds like a likely cause. Never had one so I'll just try to track it down.

I'm guessing you start at the water pump and work out? At first I though maybe the connection between the fresh water tank and the pump was loose or corrupt. Maybe I'll start there. Is there a water pickup" in the fresh water tank .... that might be plugged? Not looking forward to this due to the limited basement space to work in.