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Old 02-25-2019, 02:15 PM   #1
City: Essex, CT
Country: USA
Join Date: Jan 2018
Posts: 13
Onan MDKAV Starting problems

Hi, I have a 9KW Onan Quiet Diesel Gen Set Model MDKAV that always starts at half voltage 120V then pulls in at 120V. Most of the time, it trips out and stops the Kubota motor and has to be restarted.
Its been on the hard here in CT and I'm looking for any tips and suggestions for when I can get back on it in a few weeks.
The only thing that seems to make sense is the regulator card is putting out half the field voltage which might be a bad diode in the full wave bridge, assuming it has one of those.

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Old 02-25-2019, 04:49 PM   #2
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City: Inside Passage Summer/Columbia River Winter
Country: USA
Vessel Name: Alaskan Sea-Duction
Vessel Model: 1988 M/Y Camargue YachtFisher
Join Date: Jul 2012
Posts: 5,682
I have an 8Kw. Check the safety stuff such as water temp, oil pressure, exhaust heat. there is also a circuit breaker. Mine went bad.

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Old 04-08-2019, 12:33 PM   #3
City: Essex, CT
Country: USA
Join Date: Jan 2018
Posts: 13
Thumbs up Onan MDKAV voltage adjustment

Finally got on the boat last weekend and saw immediately the generator tripping out on startup and throwing an over voltage code. This was being caused by a large overshoot due to the regulator card with slow response. After finally getting it to start by preloading it(thats against the rules!) I noticed the output voltage was 112.2VAC @ 59.97HZ. With DC input power at 13.7VDC I went ahead with the standard voltage adjustment up to 120.2VAC 59.97HZ according to the Onan manual.
The Genset starts perfectly every time!
Most AC loads can tolerate voltage swings of several percent, however a generator is still tuned to run at its nameplate voltages within 1-2%. Being that far out of tolerance was too much for it to handle.
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