Was the gauge working before the starter build? I believe the gauge cycles through all lights and LCD bars to verify proper operation (self diagnostic test), then it will read the inputs it is receiving from the sensors. It will do this each time you press the start button, even if the lanyard is removed; it automatically turns off after 30 secs.
If you have more gas in the tank than you have bars, then you probably have a bad float and/or a bad board in the in the fuel baffle. You can pull the baffle out of the tank and check the float, but be sure to check it in gas (not water) as the specific density of water is greater and may hide a small air leak. If you need a new float OSD has them. If that is not your problem then is probably your board. The fuel gauge works by having a series of vertical gates on a circuit board in the baffle. the float has a magnet in it that creates a resistance signal when it crosses a gate. There is a small internal fuse on this circuit board that can blow if the electrical system is shorted or overloaded (i.e. jump starting). There is a thread on here that talks about testing the baffle to make sure the magnetic gates are functioning properly, as well as the fuse. If you are lucky you just need to replace the fuse, and if you are really lucky you just need a new float. From what I have read, most people (not me) don't go any further, since new fuel baffles are expensive on ebay or through osdparts.com; however, if you need a working fuel gauge, then I recommend a used one from westsidepowersports.com; they test them before they send them out (at least mine worked when I got it).
Regarding the speedometer, check the magnetic wheel on the back of the ski, as these can break, otherwise it i likely the sensor mounted to the shoe or possibly the connection inside the hull. There is also a thread that describes testing this unit, but I wouldn't spend any money on it. Apparently these were often called "hope-o-meters", because they were wildly inaccurate and you hoped it was telling you the right speed. If you need to know your instantaneous speed, I would suggest a GPS based unit; however, if you just want to find your top end I would use your phone and the waze app.
if you cant find the threads on performing the electric tests, I might be able to find them. Good Luck
