I went driving for the first time by boat. Work well, but the fuel gauge shows empty. The speedometer shows the zero, that does not work. A gas sensor shows the 0.90 ohm, or I guess it work?
First... please don't keep posting. There are only a few guys here that watch the Mercury section. Give it at least 24 hrs to get an answer.
Did you try to ground the sender wire yet? (as I said 3 days ago)
If your fuel and Speedometer both don't work... I'd say that there could be a problem in the wires coming up to the dashboard. Have you checked all the wiring with a volt/ohm meter?
Do you have the manual for your boat? You rally can't work on it without the info in that book.
Seadoo stopped selling parts for these boats 6~7 years ago. To get a replacement... you will have to find a used gauge. OR... try to adapt a generic boat gauge.
OR.... if you have a speedometer shop near you.... you may be able to get it fixed.
Dr Honda.....had same problem with my 250 optimax swap. Installed a new/used gauge I found at local boat store who was parting one out. Soon as I hooked up wires gauge came alive. Great diagnose for above problem!