Did you check the exhaust ports in the cylinder?

Yes I did and they were clean.

I suspect the "Run" section of the Electronic Ignition Coil is out, it is running on the "Start" section so never "gets off the ground".

Walt Conner

Still have the mower, still runs very rich. Changed the coil per Walt's recommendation - no difference. Anybody have any ideas?

Did you rebuild the carb? If the float valve is leaking, it can run rich. One clue on that problem is gas blowing OUT of the carb and saturating the air cleaner.

Drain the gas tank, reconnect the fuel line and start the engine. Does it speed up right before it quits? If it does, it tells me that it has good compression and will run on the right mixture, and it runs poorly now because of a rich mixture. You said it has no choke, so it must be 'primer-start', but you didn't mention pumping the primer to start it.
If it does not speed up when running out of gas, the mixture may be okay but there is another problem. You also didn't mention excessive smoke - if it's too rich and you have the right amount of oil in the fuel, it will be blowing clouds of blue smoke.
If it's not smoking, the next place I would look is the upper and lower crankcase seals (shaft seals). The 2-cycle depends on crankcase pressure and vacuum to run properly, and the seals go bad over time, sometimes popping out. You have to do major disassembly to get to them, but a clue is excessive black goo around the lower seal. If it's a self-propelled mower, the crank pulley has to be removed to get the old seal off and the new one in. Basically you pull the engine to do this. The crankcase is in two pieces and the gasket material between them could be leaking, but usually it is only the seals. You have to remove the flywheel to get to the upper one.
Hard to diagnose without being there but just a few things to check.

Thanks saxman1 for the lengthy and thoughtful response. I inspected the shaft seal and it appears to be in pretty good shape - no excessive oil or dirt around the seal. If my thinking is correct, if the seal is bad, the mower would be hard to start and may run lean due to the decreased vacuum available to suck fuel into the crankcase. My mower has neither of these problems. It starts fine with a press or two of the primer bulb.
I also shut the fuel off and let the mower run until it was out of fuel - ran rough right until it quit with no increase in RPM before it died.
When the mower is running, there is the typical blue smoke that you get when a 2 cycle engine is running rich.

To answer bogman's questions, I have not rebuilt the carb but I have removed it and cleaned it. I think if the float valve was leaking, fuel would continue to leak out after the engine was shut off. I inspected the float valve and it seems to be fine. Air cleaner does not get saturated with fuel when it is running.

Anyone ever have trouble with the reed valve on these mowers causing them to run rich? Any other ideas.

Thanks a bunch!
Jim.

If the reed valve was bad, it would still let in the air but it couldn't hold the pressure on the piston down stroke, blowing fuel and air out through the muffler. This would result in a lean, low-power condition.
How about a loose jet in the carb that allows leakage? IIRC, there's also a way that a bad primer can cause flooding - does it have a primer button?

Yes it does have a primer button.