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Generac Liquid Cooled Generators Troubleshooting Questions, Answers, and Information About Liquid Cooled Guardian Generators

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Old November 5th, 2012   #1
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Join Date: Nov 2012
Posts: 1
Default Bosch governor actuator function??

I have a 2006 era 35kw Propane Guardian (MDL 5259T). I has never operated in a storm/disaster, only operated in the exercise mode weekly. Since it was new I have put about $4k into various repairs/upkeep. So, with the latest failure of the generator I've decided to "get informed" and learn how to fix it myself. I am competent mechanic, and have moderate experience around generator maintenance. However, after many, many hours of my troubleshooting (after the local service tech spent an entire day working on it) I've narrowed the non-starting issue down to 2 possible causes.
Either the Bosch Actuator/Governor (PN-0E4395), or the Bosch Governor Driver (PN-0E3161).

My question concerns how the Gov actually operates during the crank/start mode? I find that he Governors butterfly-valve does not open, but actually closes about 1mm further from it's static "cracked" open position. This obviously prevents any vacuum at the inlet side of that butterfly. I assume that a vacuum is necessary for the Propane to be delivered to the intake, plus the engine needs air to run.

Is this the normal position of the Governor during starting mode? If not, and it should be open, should I suspect the Gov-Driver unit as the culprit? If so how would I troubleshoot that module without first spending even more money on a maybe item?

Thanks in advance for your help with this issue.
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Old November 6th, 2012   #2
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Join Date: Apr 2012
Location: Northern Maryland
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On the Bosch governor the butterfly snaps wide open before the engine starts to crank, you can hear it. To confirm it I take a long screwdriver and put it down the throat of the gov. body and then attempt a start. I then actually push open the butterfly and the unit normally starts. You can take a 9 volt battery and jump it to one of the pins in the connector to verify that it can work, I would have to find a manual to know which pin. I normally find the governor driver board has failed, I just plug a new one in and if it takes off then I bolt it in place. The govenor driver has been a weak part since new on those units and they had a lot of premature failures but have gotten better over the last few years. If this is your first, you are lucky. Good Luck, Peddler
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