Kohler Gen Output 30-170 Volts

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blackhawknoe

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Joined
Sep 11, 2014
RO Number
33748
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Newbe to the site and glad to be here...

Having a voltage regulation problem with my 250hr 2006 Kohler 7.3ECD generator. Its the computer controlled, fuel injected low CO with catalytic converter version. Still has the Kawasaki vtwin engine though. Anyway, when running the voltage output rapidly fluctuates anywhere between 30 and 170 volts, stabilizes at 120 volts for a short time and then starts fluctuating wildly again. It does this under load and when unloaded. Frequency output via the main display remains pretty constant within +/- 1Hz or so. There is no sound of the engine missing or speeding up or slowing down. Even stranger is there is no code for high or low voltage being displayed at all (Code UU for example) and the gen will not shut itself off due to the voltage fault. I just replaced the SCR bank and it didn't help. Next the service manual says I need to separately excite the field coil with a 12V source to diagnose whether its a stator/rotor or computer/wiring/SCR issue. Looking for any wisdom out there before digging in deeper. Some others have reported similar issues from fuel problems but I'm having trouble seeing the connection. Gen has the new style water bypass for the exhaust. Any ideas or similar situations? Thanks!
 
Welcome to the forum.

The new computer controlled gens are difficult at best to work on. The way they generate and produce power is completly different. Try this first, apply a resistive load, something like a space heater, fan, drill, portable cook stove, etc. Turn it on to its full load that the appliance will do, and test the voltage again, do not use the display panel, use a volt meter plugged into an outlet. See if your getting the same voltage swings as before. If not, unplug the load and test again. Is it still swinging? Does the meter show the same as the display panel?........D.......
 
You may have a problem with the voltage regulator, or you may have to check the brushes connection. When this happen the generator hunts? Can you connect a digital voltmeter at the genny terminals and check the voltage.
 
Are you checking voltage output at the generator or at the panel. that unit will shut down at more than 10 percent over or under voltage but it checks its self at the output. I would check the neutral wire both at the gen and the panel that is where you will find your problem.
 
Thank you for the great responses. The voltage is definitely fluctuating at the panel and outlet, both with and without a resistive load. The voltage swings are being shown on the generators digital display but the generator is not coding or shutting itself off. I need to see if the wiring diagrams show if the voltage display senses downstream from the controller...it could indicate a wiring issue at the external connection. Anyone think this could be a ground reference issue?
 
You have a loose neutral (the white wire) at the connection at the stud in the generator electric box or at the shore power panel transfer switch. You are making this repair harder than it is. Check these connections first.
 
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