Well I flushed the fuel system yesterday, then nice warmup.
I flushed the fuel system by removing the fuel line at the joint behind the check valve down stream of the filters but before the injector pump. The check valve is the little fitting located below the oil pressure gauge typically with an elbow installed to allow the lines to fit without kinking. I had previously wiped the fuel tank clean and rinsed it with mineral spirits, as well as cleaning the screens located on the bottom of each fuel pump. If you havent added petrolium jelly to the caps like rustystud recommended it works great, effortless to reinstall. Since diesel fuel is cheaper than mineral spirits and I had some seafoam left over from a different project I decided to use them to flush the system. Plus I'd have the added benefit of not having to drain the fuel system afterwards, just bleed the air and reconnect the fuel line.
Since the generator seems to be well maintained I opted to simply flush the fuel system and cross my fingers that there is no real varnishing, and if there is any varnishing I hope that enough use and exposure to seafoam/fresh diesel will dissolve it. I took an empty bucket and held the disconnected fuel hose towards the bucket while running the pumps. After the filters and strainer filled, fuel began squirting out the hose and after about two gallons it became a pulsing but steady stream indicating the air has been flushed out of the system.
I reconnected the fuel line and let the fuel pumps build pressure. The ticking of the oscillating pumps slowed as expected as the pressure increased and everything sounded healthy, no leaks in any of the lines, on the injector pump, nor on any of the gaskets on the fresh filters I had installed.
The weather here in Wisconsin was a nice 37 degrees so I opened the garage to let the generator exhaust outside. The one good thing that came from dumping the genny on its side was that it up righted with the exhaust oriented out the garage door
I set the throttle about half way out, and turned the dial to preheat for around 60 seconds. Turned the knob to the start position and she cranked to a healthy run! I adjusted the throttle to hone in on 60hz and let her purr!
Good oil pressure, no oil or fuel leaks, she runs like a champ!
I let her run for about 25 minutes before my wife grew sick of the noise coming from the garage, now I need to conjure up a way to load test, probably when the wife unit is too busy to notice