I agree with dimurrrw, there IS a city hook up somewhere.
Fill the tank with water, and make the tank drain is not open by looking for water running from under the RV, turn the pump on, and leave it on, now go outside to the water heater, open the door, and pull the handle on the pop off valve. Now, smoke a cigarette, drink a beer, whatever, and wait till you get a steady stream of water coming out. should be 5 minutes or so. If you never get water, the water heater may be in winterization mode, not to worry, should still get water at faucets, so go check them one more time. It takes a while for the pump to prime and get all the air of the lines, especially the water heater, AND NO, the cold won't work till the water heater is filled!
If in that time, the pump never shuts off, then you don't have much pressure coming out of the pump.
2012 Ford F250 ext. Cab 4x4
2002 Jeep Wrangler Sahara
2008 Yamaha V-Star 650 Classic
2008 Work and Play 18LT