Re: Dash Wiring...Help?
Look at the back of the gauges that aren't working. Each gauge has a +12 volt terminal, a ground terminal, and a sense terminal. All of them have a terminal for an internal light. If you don't have a test light or a digital multitester I suggest you get one and learn how to use it -- especially if you intend to do electrical troubleshooting yourself. Unless a wire has fallen off a connectioni, there is little else you can do without these tools. If the gauge doesn't have +12 volts or ground when the key is on the gauge won't work. If the sender (fuel gauge, temperature, trim, etc) wire is disconnected or loose at the gauge or the sender itself the gauge won't work. If the sender is bad the gauge won't work. You can test the gauge by "briefly" jumping the "S" terminal to the ground terminal. This should cause the gauge to peg full right. If not, the gauge does not have a ground, does not have +12 volts or the gauge itself is bad (rarely the case). The metal shell of the fuel sender at the tank must be grounded as well. A good sender will measure 33 ohms when full, 109 ohms at 1/2 full and 240 ohms empty. All of those readings are approximate. The speedometer does not have a sender. Chances are the pitot (either on the engine or the white thing hanging down off the back of the boat) is plugged with debris.
Here is a diagram of the fuel gauge system.