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Hank F.
Hank F., RV tech - emphasis on gensets
Category: RV
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Experience:  RV tech since the beginning of the millenium.
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Onan 4KYFA26100K does not put out AC while running. Just

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Onan 4KYFA26100K does not put out AC while running. Just stopped mid trip last month, no issues prior to that. Have continuity through genset breaker, P6-6 to breaker and P5-6 to ground. While genset is running and breaker on have 0 VAC, with breaker off I have ~20 VAC. Also verified ATS in trailer is good. Shore power works as advertised.

Hello, my name is ***** ***** I am going to assist you with this.

If the genset is running, it is producing voltage. If it really were only putting out 20 volts, it would be shutting down with a code 12.

Where exactly are you trying to measure voltage at?

Have you checked your meter against a known power source to make sure the meter is not malfunctioning?

Customer: replied 9 months ago.
the meter works as it should. I'm checking voltage at the CB. With the breaker on I have zero vac, but off it reads ~20, fluctuating 1-2 volts. I bypassed the CB to eliminate that as a problem, still did not get any output voltage from gen

Are you sure you are testing on the input side of the breaker, and not on the output side?

Customer: replied 9 months ago.
Two wires going to the breaker. A black one labeled "load" and a white one labeled "line". Reading those two. The white wire goes to P6-6 and the black goes into the trailer.

It is sounding like you have a bad stator.

To test it, you must be able to remove the top cover, and this usuallymeans having to remove the genset from the coach.

Can you get the top cover off, or do you have the capability/facility to remove the genset?

Customer: replied 9 months ago.
No I cannot get the top cover off of it. I was able to remove the two outboard bolts to gain a little more access to P5 and P6, but it didnt give me a whole lot of extra room. Is there another way to verify the stator is bad without removal of the Genset?

No, you must be able to remove both of the stator plugs, and get down inside for testing.

Customer: replied 9 months ago.
Okay. Once removed will I need to start the genset for additional troubleshooting? I can probably get it removed in the next day or two with the help of a buddy. Once removed what step do i need to take?

With the stator unplugged, it will not start.

But I recommend leaving it out until it is done - and this means bench testing it once repairs are made.

I have uploaded instructions on testing the stator. Click here to download the instructions.

Customer: replied 9 months ago.
Okay let me get it removed and run these tests and see what I have. What leads you to think it could be the stator?

You state that you are not getting voltage to the circuit breaker. But as I said, if the genset is not producing power, it would shut itself down. So the controller is seeing voltage from somewhere, and it sees reference voltage from a different winding in the stator than the power windings.

Customer: replied 9 months ago.
Okay makes sense. The way i described reading voltage at the CB, is that the correct way i should be looking for voltage?

Yes, you check from the hot leg to neutral.

Customer: replied 9 months ago.
I will let you know what I find. Thank you.


Have you checked on this yet?

Customer: replied 9 months ago.
Hank, thanks for the follow up. No I have not checked it yet. Had something come up.

I understand.

Customer: replied 9 months ago.
Hank just wanted to give you a heads up. We have been getting slammed with rain so I haven't pulled that genset out yet.


Hank F. and other RV Specialists are ready to help you
Customer: replied 9 months ago.
Hank thanks for everything. Found the issue while removing the Gen. there was a second junction box the gen output wires came into. Looks like the wire nuts just melted and grounded out on the junction box. Changed the nuts and wrapped with elec tape. Works 5.0 now. Thanks for all your help, I never woulda found it if you didn't tell me to pull then gen, as this junction box was pretty hidden in the front storage compartment.

Good deal.