As a wiring technician/enthusiast, I have always been a stickler of sticking to the color code of whatever I'm wiring. Some guys don't really care about the color code...they just want the damn thing to work. However, I prefer the color code for a few reasons:
1) The wiring job looks like a professional did it
2) Easier troubleshooting for you
3) When you go to sell the boat, everything is done to a standard to allow the new owner to troubleshoot easier
So here I will post the marine standard electrical color code for jet boats:
Black - All grounds
Red - Constant hot (all wires that have 12 volts on them regardless of key switch position, "BAT" terminal on key switch)
Purple - Hot In Run (switched hot, controlled by key switch i.e. ignition, gauges, etc, "IGN" terminal on key switch)
White - Hot In Start (runs the starter bendix or aux solenoid)
Light Blue - Oil Pressure Sender; "S" terminal on Oil Pressure gauge
Light Brown or Tan - Water Temperature Sender; "S" terminal on Water Temperature gauge
Grey - Tachometer signal from ignition; "S" terminal on Tachometer
Orange - Bilge Pump hot from switch to pump
Pink - Bilge Blower hot from switch to blower
White/Red - Fuel level sender; "S" terminal on Fuel Level gauge
Yellow - Lights from switch to lights
