The engines are fitted on a 76 Nordhavn and have performed flawlessly for the 2 years I have been onboard, anybody have any theories I would apreciate hearing them, no matter how wild. QSM11 350hp 1800rpm 5500hrs 24v Boat started and ran with no alarms or indications of problems for 3 hrs coming downriver to get situated for survey and seatrial. Right after throttling back to come onto the dock stbd engine dies and won’t start back up. Unplugged ecm and plugged back in, engine started and runs at idle at dock. Next day both start no problem, haul out, on launch both start up, while backing out of slip port engine dies. Multiple alarms and errors on port. Shut down stbd. Both engines will turn over and start but as soon as start button is let go, they die. Cummins tech plugged into motors and find stbd ecm does not send power to fuel solenoid. Port fuel solenoid measures 21v stbd 0 Port sends power and all points to engine should start and run but does not. New ecm fitted on both and same problem and faults Ecm’s switched port to stbd -same problem and faults Stbd during course of the day blew battery fuse twice but could not get it to blow again. Sea fire system bypassed and checked-no effect. The plan is to next change out the fuel solenoids but suspect this to be a symptom rather than cause.