Kohler 5E generator on my boat got wet there is no power at the 120 V. distribution panel now. Any ideas on where to start troubleshooting ?

1. First you must clean it all, especialy the generator, windings, AVR etc. if it was wet with sea water (better do it with fresh water or electro-clean, than other liquids). Then you should dry it well (with a hot blower) for about, but not less than 24 hours, before starting.
2. If you already started it wet, or it got wet while running, you may have some parts burned, with low insulation of cables, windings etc. Check the AVR, rings and brushes (if any) and other electronic boards for visualy burned elements or check the semiconductor elements (diodes and transistors) for proper qualities.
3. You should check the gen. windings insulation resistence to hull (gen. iron) [all stator and rotor windings]. It should be more than 100 kOhm in order to let you start the generator motor.
4. When dry and clean, with no burned elements you can start the engine. If it reaches its normal speed - measure the voltage on generator terminals, if it is OK check the connections (breakers, fuses) to the distribution panel. If it is very low under 30 V AC, the problem may be in AVR (Auto Voltage Reg. - Field DC supply)
5. If the voltage is under 10 V AC, you may need to recharge the magnetic field with a 12 V battery connected shortly to field terminals - +/- respected.

I have a kohler 45ckm21-rv the output is onley 78 to 80 volts whear is the problem