RV Repair: air in fresh water going to pump, air gaps, input side


Question
RV Repair: air in fresh water going to pump, air gaps, input side
Fresh Water Line  
I have a 2010 Jayco JayFlight.  To make the question short, I have air in the fresh water coming from the tank to the pump (I have a length of clear tubing in the line from the tank to the input side of the pump and can see the air gaps water flow).  The pump will run for a minute, or so (pumping air and water) and then loose its prime as there is no water coming up the line.  I have checked all the connections in the line (that I know about) including where the line connects to the tank. Any suggestions, or thoughts?

Thanks in advance!  -Verne

Answer
If you pull the lines off at the strainer, will water come out of the tank freely?

Do you have access to a compressor so you can blow some air into the tank to see if it has any blockage?  

Will it pump without that strainer?  Unscrew that strainer and hook up lines to the pump without the strainer and see if it improves.

If you hook up a water supply, like a garden hose, will the pump move the water?

After all these checks, it could be the pump is not able to prime itself because of blockage in it, or it is just plain bad.