1981 20KW Kohler 20ROP63 Issue

[MVCaprice]

Sams Forum,

We are having an issue with our Kohler 20KW Genset which we are hoping to run down. Given that these are somewhat common generators we thought this would be a good place to ask. So far some local shops have looked at it, but they have been unable to diagnose the issue.

The symptoms we are seeing is that if there is more than a 30 AMP load the voltage begins to drops from 220 to below 190 and even further if additional load is added. One potential diagnosis that was kicked around is that the generator unit itself is bad, but we are unsure.

The set has about 1500 hours on it.

Anyone have any suggestions?

[Boatsb]

fuel.

[Andy B]

Could be a weak capacitor,check frequency when the voltage drops if it stays around 60hz then problem is most likely in the back end.

[bigbill]

does it have a voltage regulator?
what about the governor? might not be keeping the engine up to the task

[MVCaprice]

Its not the engine dropping rpm, and its not fuel. There's no voltage regulator that I can find on it.

[davidwigler]

You're sure the rpm stays constant when voltage declines under load?

[MVCaprice]

No change in rpm that I can tell

[Andy B]

Frequency is directly related to rpm, if its low rpm is low,below 1800,if its high rpm above 1800.

[MVCaprice]

OK. Thanks guys. We'll take another look at the RPM and Frequency and post back.....

[carolinacoast]

we had a similar issue, and it was a dirty secondary fuel filter on the gen that was not actually changed until I changed it from suggestions from this board. Despite me having an invoice to the contrary.