1. Double check to make sure that you have water in your freshwater holding tank. If the tank is very low or empty the water pump has nothing to pump.
2. Check all the water lines leading to and from the water pump to see if you have a loose connection or cracked water line. Start with the water line leading to the pump from the freshwater holding tank.
Once you get to the pump you may want to remove the water line from the suction side of the pump to determine if there is water in that line. Have a bucket or something ready to catch the water that may come out of this line. Slowly loosen the connection to the pump. If water starts leaking out when loosening the line you know that you are getting water to the pump; you can now just retighten the line and move on to step 3.
If you loosen the water line and no water comes out, then you know that you are not getting water to the pump and the problem is in the water line leading to the pump. It could be that there is a crack in this water line or a blockage of some sort. If you have ever run the water pump with the tank empty, you may have to re-establish suction on the water line. There has to be water in the line for the water pump to create suction. Try filling up the water line with water and then reattach it to the pump. Try running the pump again to see if you are now getting water to the faucets. It may take a minute or two for the water to start coming out of the faucets. If water is still not coming out of the faucets move on to step 3.
3. We now know that we are getting water to the pump, but we are still not getting water to the faucets. Even though the pump is running, it does not necessarily mean that the pump is good. If the impeller in the water pump has broken or is free-wheeling the motor can run all day but there will be no water flow.
To determine if the pump is actually pumping you may have to slowly remove the water line from the pressure side of the pump, with the pump running to see if it is pumping water out. Again have some buckets and clean up materials ready to catch the water. This is a two person job. One person is at the water pump and the other person is at the pump switch. With the pump running slowly loosen the water line; it will become very apparent very quickly whether the pump has pressure. If water only trickles out when you are removing the line thet means the water pump
needs to be replaced. If you have good pressure; move on to step 4.
4. We have determined that we have good water pressure coming out of the RV water pump, so we now know that the problem is between the water pump and the faucets. Check all the water lines leading from the water pump to the faucets to for leaks cracks, etc. Repair and replace as needed. Also check all of the water shut off valves located in the cabinets under the sinks. These water shutoff valves are similar to the ones you have under the sinks in your house. Make sure that they are all in the on position.