Rangers38
I have a 10 KW NG Generac that I installed in 2013.  I am experiencing constant overspeed shutdown on the weekly test. A while back I tried the reset of the controller board by pulling out the 7.5 fuse. That really didn't do anything. A few months later the controller board failed. I purchased a new one and installed it. The unit ran fine for a few weeks, but now the overspeed failure is back. When i run it in the manual mode, it looks to me that the governor linkage from the small electrical componet which i believe is the stepper motor does not seem to operate correctly. The linkage moves freely without any lockup. It seems that the linkage allows the unit to run to fast and it goes into overspeed and shuts down.  So I am assuming its the stepper motor? I should also mention that my utility company ran a new gas line to my house and installed a new meter, as they were upgrading the gas mains on my street. This problem started around that time. Not sure if that has anything to do with it? Anyone experience this? maybe have any input as to how to fix this situation.

Thanks in advance.
John
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Peddler
When the unit starts does the throttle arm move to the wide open position when cranking and then back to about the middle when it starts?  If not make sure the stepper motor cable is properly seated in the controller.  
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78buckshot
Ranger, I don't think the problem is related to the new gas service, check the stepper motor as Peddler described then get back with us.
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Rangers38
I checked it again. On the manual start it moves, not sure all the way, but does not retract fast enough before the unit runs to fast. It does seem like there is a lot of resistence moving the arm back and forth
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Peddler
Not a guarantee but I would replace the stepper motor. 
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JayH
Rangers38 wrote:
I checked it again. On the manual start it moves, not sure all the way, but does not retract fast enough before the unit runs to fast. It does seem like there is a lot of resistence moving the arm back and forth


Can you determine if the resistance is in the motor or from the linkage and throttle plate? If it's in the linkage and throttle, look for something binding. If it's in the stepper motor, replace the motor.
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78buckshot
You can pop the linkage off of the stepper bellcrank and check the movement of the throttle linkage and plates. The stepper motor will have some resistance as you move it through it's full travel, as Peddler recommended, I would replace the stepper motor if you are not able to go further with diagnostics.
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Rangers38
Installed a New stepper motor assembly today. Had to remove the motor from the new assembly and put the old mounting bracket on. The new one came with a different bracket. That was a bit tricky as I did not want to change the sprocket position when I put it back together.. The bracket is sandwiched inbetween the motor and the gear assmebly.  Fire it up several times, seems to have corrected the problem. No overspeeds.
Thanks to all who offered help and suggestions. Much Appreciated
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78buckshot
Your welcome, glad we could help.
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