water pump

[roned2]

We usually use city water so have rarely used the water pump. We are currently in a state park with no water on site. Our pump usually makes a constant noise when water is called for. Now it makes a laboring, chugging noise while the water is on similar to when there is insufficient water in the tank. We are 3/4 full at this time. Any ideas? I am not handy so solutions I hope will be simple.