1999 225hp OX66 at idle it coughs then stalls and runs rough at speed

[rtmadm00]

I have been searching through the threads to help troubleshoot my '99 225HP OX66. The symptoms are it runs at idle(600-700 rpms) then it "coughs" and stalls. Also, at speed it seems to lack power and you can hear it is running rough. So far we have:

• replaced the RACOR filter separator element
• replaced the O2 sensor, 65L-8592A-00-00and cleaned the port.
• replaced the fuel filter element on the engine, 65L-24563-00-00
• replaced LP fuel pumps 6E5-24410-03-00 about 8 months ago.
• replaced the fuel injection pump filter, 66K-13915-00-00
• replaced the spark plugs
• replaced the spark plug caps. They measured 30K-40K ohms. New ones are in spec at 5K ohms. I thought this would do it but no joy.
• checked the fuel injection pump pressure. It is 35psi at idle and around 36-37psi at 3000 rpms.
• Voltage is around 14 VDC at engine speeds above idle.

I think my next move is to pop off the flywheel and inspect the pulser coil as per thread Yamaha OX 66 experts help-I have a gremlin.

My question is does anyone have any comments on how hard it is to pop the flywheel off the crank shaft taper?

I recognize this is highly variable having removed many gears and bearings but I thought someone may have some guidance as to a "trick" to make it easier.

 

[99yam40]

I would be testing peak voltages from the charge coils, pulser coils, etc before pulling stuff apart.
Sorry I am no help with tricks to pull flywheel

 

[BrettNC]

You have more testing to do. Check for spark on all cylinders. Check compression and do a cylinder drop test. Check for water in the cylinders. A bad key switch can cause this behavior as well. Check this stuff and report back.