What happens to the water?
When you run water into that fixture, where does the water go? Does it come shooting back out at you (which would indicate a kink)? Does it fall out onto the pavement? (One of the laws of thermodynamics says that matter is neither created nor destroyed -- but sometimes it leaks!) Can you hear where it is going?
If this is your black tank rinse, and if you can get it working, it is very useful -- our old Fun Finder did not have one, our new one does, and it is really handy.