fluctuating RPM diesel motor

[Robski97]

SO for the last few weeks I've been having an issue with my stb motor . When cold ( 140 degree;s ) she lags behind the port engine. Eventually catching up. Once warmed up the lag is gone the rpm fluctuation remains ... always up or down 10 rpms ... no matter the speed or load... even idle ....After this started I changed all the fuel filters just to be safe .. all were clean.... Any thoughts....

Motors are Cummins QSC 8.3's 2006 roughly 150 hrs


Rob

 

[Asureyez]

Fluttering Heart?

Hey Rob, A 10 RPM swing isn't much, but the pulsation in RPM gives me cause to pause as I belive you have the electronic controls on your power plants. Ummm, I believe there is a vacuum advance on your engine. check the hose clamps and hose condition. Leaking vacuum most likley cause outside the black box.

Curious, does it still pulsate while under Synch. control?

 

[Robski97]

Chad i only use the sync .... By hand i never get up matched up...

prior to last few weeks .. they were always right on the money...


I do not believe i have any vaccum. Looks all electronic...


Still waiting on Tech service from Cummins to set up an appt .

Rob