Cummins S/D During Shifting

[NorthernFocus]

I searched (briefly) to see if this has bee discussed previously but came up dry. I recently had two events during which the engine shut down when shifting into reverse. Unfortunately both incidents occurred at awkward moments. One happened when pulling up to a fuel dock and the other when approaching a float/buoy to grab haul our shrimp pots. In both cases there was a pause of several seconds in neutral prior to shifting into reverse. Also in both cases the engine restarted without incident.

I was just wondering if this is another known issue with the Cummins engines or if others have experienced the same thing happening.

 

[Levitation]

That could be a lot of things
My first impulse is too look at the idling rpm. Is the engine idling too slow and simply stalling
With a slow idle, when it shifts into reverse (or forward) with the boat moving in the opposite direction the sudden load on the prop can stall it

Another, but more remote, possibility is a loose/shorted connection in the neutral switch to the key
If the idle is OK I would investigate that - and be sure it is wired correctly, you will need a diagram from the factory to check it
Now yes, I know that switch is supposed to affect only cranking, but 'stuff' happens as they say
Have you tried starting the engine while in gear
Have you gone to open water and tried docking maneuvers to see if it stalls

Beyond that is a world of possible problems - ranging from an air leak in the fuel lines to a faulty ECM
It will be interesting to see what the factory says

 

[NorthernFocus]

Idle RPM seem to be good. Though I have seen some variability as the ECM "hunts" a bit right after starting when the ACRs close and the alternator load goes up. But after everything is warm it pretty much locks in on 700rpm. But that is a good point and I'll try your advice to go through some shifting in open water and keep an eye on the tach. If it can float a bit due to alternator load surely it must do so when going from neutral into gear.

The neutral switch was the first thing that came to mind. But as you say it "should" only affect cranking and not act as a kill switch.

Well if anyone else has had this problem please chime in...