Greetings from Southern California and THANK YOU in advance for your suggestions.

My generator (4K) has been difficult to start so I finally jumped into it...

It seems that the Onan starts quicker when I keep the "prime" circuit energized while cranking. Does this sound reasonable ??

Holding the prime switch while cranking to keep the pump and ignition going during the change over from cranking mode to run mode. This change over is normally caused by the internal alternator starting to generate approximately 28-30VAC which tells the board that the engine is running and to keep the pump and ignition going. Mine is slow to come up to voltage and holding the prime switch overcomes that delay.

On that generator from hell that I worked on last August it had the same problem. I had the flywheel off for other reasons so I cleaned all of the alternator pole pieces and and also polished the inside of the flywheel where the magnets are. That eliminated this problem. I need to do the same to mine but I never seen to get around to doing it. It is much easier to just hold the button a few seconds longer when starting. Maybe some day I'll fix mine too.

From my reading of the various electrical diagrams - it sure looks like the fuel pump only runs with the prime circuit energized or from the positive side of the coil while the engine is running. Should the fuel pump be pumping while cranking ??

No, the pump runs while cranking and while running. The ignition coil, fuel pump, and fuel solenoid (if equipped) are all wired together.

And... With the priming circuit - shouldn't the pump slow down after the carburetor bowl gets filled ?? Is seems that mine continues to pump - no changes in the sound it makes... (it's the "direct replacement pump" from Applied.)

Yes it should slow down after reaching pressure (around 4 to 6 PSI). Several things can cause this. sucking air on the intake side (I doubt this or you would probably have problems running under load). More likely is the check valve inside the pump that is not sealing completely due to a piece of grit or something. It is very easy to take the pump apart and clean / inspect it. If you want a new base gasket and filter are available from NAPA because they sell that same pump under the NAPA brand name. I would screw in a tee and small fuel gauge on the output of the pump to see if this is what is really happening. A PO installed one permanently on mine.

Everything seems to work once it's running. No hunting, no stalling, 120VAC... Just a little difficult to start.

And THANK YOU Gene Fisher. From the 49er blog post on your website - I got my Onan electric choke properly wired and working.

Steve W
19873 23'
Southern California