Test the baffle and gauge since they're easy to troubleshoot without taking anything apart. You would need to locate the baffle that's clamped to the tank and then unplug the wire harness coming out of it. It should be a two wire plug with a pink & pink/black wire. To test the gauge, use a paperclip and short (connect) the two wires going towards the gauge. Now with the lanyard removed push the start button and see what happens. If the gauge goes to full, you have a baffle problem. If nothing happens, your gauge is most likely at fault. To test the baffle, using an ohmeter check for resistance on the two wires going into the baffle. You should get a reading from 0 to 89 ohms. If you get an open circuit, you have a bad baffle (fuse). If it's below full but you get a 0 ohm reading, the magnets most likely have detached from the float. If the ski has fuel in it and it reads around 90 ohms (corresponds to empty), the float may have absorbed fuel and is setting in the bottom of the baffle. Those tests should help you figure out exactly where the problem lies. If its the fuse thats bad try this sticky for the repair of the fuse: