15Kw generac generator will not start

Turns out it was the Manual-off-Auto switch that was bad. My DVM showed a voltage drop across the switch. The controller wasn't getting enough power.

One good thing about it was it forced me to really study the schematics to understand how everything worked. I'm now in the process of designing my own esp32 based controller, with wifi connectivity, to replace the stock control board.

I would do a compression test before you removed a cam.
How did you diagnose the camshaft?

Good troubleshooting on your part. Was my thoughts that the onboard battery had failed.

check grounds and the locate and check silinoid/connetions

You can check for tanks being turned off and of course if there is fuel in the tanks. If further troublshooting is necessary you should likely ask for assistance.

I suspect you will SOMEPLACE find protection fuse(s) for the sense lines from the utility. That is the first place to check.

Check the oil pressure switch



If you need further help, I’m available over the phone at https://www.6ya.com/expert/craig_3fa289bf857b1a3c

I am assuming the generator worked fine before the oil change. Now that you have done the oil change the genset does not start. These generators have a safety switch, which is basically an oil pressure switch that keeps the engine from running when there is not enough oil in the engine. Make sure that there is enough oil and if there is, look for a wire that runs along side of the engine to a round component. disconnect that wire and try starting. If it does not start then try to ground out the wire to the engine block. If this does not work, then there is other engine problems.

oil temp also? and or pressure. fuel shut off valve? switch bad not keeping power on run side?

That sounds just about right, if the relay contacts get welded together it sometimes takes out the driver on the printed circuit board. As you found out, 12vdc from 23 to 194 makes the transfer switch move to the Generator position, relay not energized makes the ATS move to the Normal position.

You can make a nice test function by installing a 10 amp contact switch in series with either the N1 or N2 terminals. When the switch is open the generator thinks the Normal power has failed.

Regards,
Carl