[Snowballs]

Did you ever get more information on this? I have the same genny and the same problem. Runs well for 30 mins then starts to hunt and eventually dies. I have to check and verify my battery wiring.  I may just try and run it with out the onboard charger operating and see if that takes care of my issue. Did not think that they both would be charging.

98 3500 open

I did. Apparently the electronic governor is sensitive to voltage from the connected start battery and in my case where using the house batteries as the start if they drop below a certain level which they did after running dc loads it can cause issues. Further the charge circuit off the generator is relatively low and unable to properly charge the house bank which in my case consists of 2 - 130ah batteries. On top of that if I ran the ac powered Victron charger I was essentially running that in addition to the generator charge circuit. I noticed the ac charger would never drop below approx. 35 amps when running off generator power as opposed to eventually dropping to a trickle charge when on shore power. I wound up installing a dedicated start 800 cca battery (westerbeke recommends 600-800 cca). Seems to have solved my problem and ac charger now fully charges both house and engine banks and drops to trickle when running off generator power . Beyond this I’ve heard the fuel pumps are known to shut down after running for a bit - heat related. Make sure to check raw water feed too. I’ve had blockages in the elbow on the feed side of the strainer that caused reduced flow and eventual shutdown either exhaust or water temp sensor overheat. The elbows on the sea cock and into sea strainer should be removed and go direct hose. Elbows clog easily. Hope this helps.