Yamaha F225 High Pressure pump runs continously

[choogenboom]

2004 F225. Ran it offshore yesterday for about 14 hours, runs fine all the way to the dock. An hour later I start it and barely starts, will run if I give it neutral throttle.
1) high pressure Fuel pump runs continuously with ignition in run and engine not running.
2) fuel pressure 46 PSI engine off (but ignition on, so high pressure pump running), 40-42 PSI on.
3) Will not idle, runs rough at any speed, "loads up"
4) all spark plugs black/sooty
5) ECU replaced about 5 years ago after a lightning strike
6) ISC valve not audibly ticking when ignition switched off
7) Have YDS but have not connected it up as yet.

Suggestions?

 

[choogenboom]

The YDS showed injector open time varying between 2.5 and 7.0 ms which was clearly not right. I have twins and the other engine was a steady 2.5 ms at idle.
After disconnecting the ISC valve started running smoothly. How a non-functioning ISC valve causes the injector open time to vary wildly is a head scratcher. The high pressure pump still runs continuously with key in run position but engine not running.