If you take the lead off the sender and see if it pegs or stays at 0, then go to ground and see if it changes. If that gets you to go from 0-pegged then you do not have a wire issue you have a sender issue. If when you run this test it does not work then do the same test at the back of the guage. If it works there you have a shorted out wire and you will have to run a test on the wire.

i didnt read the entire thread if this is a repeat.........
don t reuse a guage that has been pinned it is only good for the garbage can

I just got time to test what my problem was because the boat was in storage. I disconnected the wire from the sending unit and turned the key and the gauge still goes to pinned. Then I connected the wire back up to the sending unit and disconnected the sending unit lead on the back of the gauge. I connected the lead on the back of the gauge to ground and gauge goes to zero. I also put a 2.2k ohm resistor(only one I had in at home) in series with the gauge and sending unit and the gauge read just under 20 PSI. Not to sure what this means yet because I thought the gauge went from 0-88 ohms

I just went out to the boat and bypassed the orginal wire from the sending unit to the gauge to see if there is a short in the wire, but it appears to be doing the same thing. Any thoughts?