View Full Version : New 3GM30 idles too high

08-15-2008, 05:13 AM
I've installed a new 3GM30 and it runs extremely rough at anything under 1100 rpm. It runs smoothly over 1100rpm. "Rough" means it seems as though it will vibrate off its mounts. The fuel pump and injectors have been professionally serviced prior to starting. For now I'm assuming there are no issues with the fuel system. Any suggestions as to what I could try?

08-15-2008, 11:28 AM
I too have just installed a 3GM30 and it idles rough as hell and sounds like an old Ford tractor. Until I load it down and then it purrs like a newborn kitten. It is my understanding that they are only happy when they are under load.

03-08-2009, 10:58 AM
"I understand they are pleased to be under load and running 3000rpms or better. Check engine mount bolts often if you have to idle alot, I suppose.

Does anyone have any idea as to the age of 3GM30F engine #12416 or about when it was manufactured?? Thanks."

03-08-2009, 11:44 AM
"Check the S/N Tag. Is there a letter E printed in green on the left of the stamped in S/N ?.
Early engines were assembled in Japan and later engine were assembled in Holland and there for had a letter "E" printed before the stamped S/N Also the early sea water pump had numbers or little markings on the raw water pump. The Europe engines assembled Johnston raw water pumps, that are made in Sweden"