New to me 2013 Yamaha F115LA problems/ alarms--frustrations

[kneedragger]

I purchased a used 2013 115 four stroke with 230 hrs from a dealer in the panhandle end of Sept 2018. It came with new switch, used wiring harness, and used 704 binnacle. Later i purchased used tach and speedo gauges from Ebay. I also bought new cables from Iboats, and rigged it in Dec. I finally water tested it 2nd week of March 2019. It started throwing an alarm after about 3 minutes of use and would not go off, and would only idle to about 2500-2800 RPM. So I took to a local dealership that was a Yam. Tech, because they could get to it quickly. New plugs, and new tank (because they thought my old tank was pulling a vacuum, they said it was cooling fine, (and $480) later, It still does the same thing. Idles fine, and won't power up, and throwing a alarm. After almost 6 weeks of "waiting for the local Yam rep to show up" to connect it to the computer diagnostic system because "we don't have one" I said enough. Now at the second local dealership near me in central Al, and they discovered a crack in the VST float, but after a water test father's day weekend, No change. Still doing the exact same thing. The ONLY difference is the gauge was connected by the second dealership, and the oil sensor indicator on the gauge is flashing. Second dealer has checked the ECU with another one, and said it was fine, after thinking it needed to be "reflashed", I have asked repeatedly if they have checked it with the computer diagnostic to tell if it is throwing a "code", and have been told it has been "reset". I have also asked them to determine if it is an oil pressure sending unit. ANY SUGGESTIONS?