Water pressure gauge not working..

Any help is appreciated, I have a 2010 Ranger Z521 powered by a 2009 Yamaha 250 HPDI series 2. My water pump gauge quit working last month. I brought it to the dealer they said the gauge was bad "so I ordered a new gauge from Ranger (still under warranty) I replaced the gauge,,,, still not working. The mechanic "guessed" it was the gauge because my engine is pissing water very strongly. My water pump is also brand new. I don't know what wires at the plug should have power and what should be ground, If I knew this I could check it with a test light.
On my engine on the top left side there is the engine temp. censor,,,, on the opposite side of the engine in the same place there is a (looks like another type of censor) with a black small black hoses crimped on to the top. It is brass. Is this the water pressure censor? And if it is, "could sand clog the end of it and cause my gauge to stop working. I was gonna remove it, and check it, but I wouldn't have been able to re-crimp the hose back on.
If anyone could let me know what to check that would be great, I have been a auto mechanic my whole life so I am familiar with the way things work.
Thanks in advance
Tom S.

it sounds like it is clogged

What do you think is clogged, "the sending unit" ?? If thats what you are are talking about, am I right about what censor I think is the water pressure censor ?

Thanks for helping !

pull out the sensor, then use compressed air from the gauge tube to blow toward the sensor

Thanks for your help, sincerely.
The hose from the sensor doesn't go to the gauge, thats was what was confusing me. The gauge only has wires running to it. I just removed the access panel to the bilge area, "the hose runs to a electric / diaphragm transducer mounted in the bottom of the boat. It's too dark to do it now, tomorrow I am gonna remove the the sensor "check it for a clog, then blow out the hose. I have already removed the poppit valve and inspected that, so hopefully I will get this straightened out tomorrow.
Again, thanks for your help.

Wow, a lot of good information. I want to fit it.
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Problem solved,,,,

The diaphragm / electric switch that is in the bilge area had ONE tiny, tiny piece of sand clogging the hole. The hole in the switch is smaller then a pin hole (new shirt pin).
I used the tip of a small drop shot hook to remove the ONE tiny piece of sand. I also blew out the line to make sure the hose to the engine was clean (both ends disconnected).

All that grief was caused by ONE microscopic piece of sand.
Thanks to everyone who posted here trying to help.