Onan 4k generator

[Joestein]

What should the ac Volt's output be on a generator? What is it with nothing on and what is it with everything on? I know it drops as you start the microwave, ac, tv and so on. I'm testing from one of the plugs in the kitchen area. Any help is always appreciated.

[Solo_RV_Guy]

Typically 117 to 122. Expect about a 2 volt drop with a 20 amp load.

[Isaac-1]

117-122 is typical as noted above, but allowed output spec variation is more like 115-125VAC

[Joestein]

So with nothing on it is supposed to be 122-125? And with load it should only drop 3? Mine is 140 with nothing and with ac, microwave, and various thing it's 120.

[Isaac-1]

That is way too high, assuming you are using an accurate voltage monitor / multi-meter. If it really is that high then your voltage regulator board has went bad. Most versions of the Onan 4000 have a voltage regulator board integrated into the control board, but given you have a 1997 model, it may have a separate voltage regulator board, as I think the switch over date was around 1997.

[Joestein]

It is a separate voltage regulator. It is also a brand new Onan one from the factory.

[Isaac-1]

It still might be defective, or it could be a wiring issue in the wiring harness going to the voltage regulator causing it to stay in full boost.

[Solo_RV_Guy]

The 20 volt drop makes me think there's a bad connection between the genset coils and the load. Do you get the same voltage drop on shore power?

[Joestein]

I haven't checked on shore power.

[Joestein]

How do I turn the voltage down , set the carb, and make sure frequency is right.

[bigchick]

if brand new from factory it is under the manufacturer 2 year warranty. take it to onan.

[Joestein]

The regulator is new. Bit the generator is 22 years old. I bet that the warranty for that is expired. Haha. Thanks everyone for the help.

[exrench]

Lacking better instrumentation, plug an analogue clock into an outlet and note how much time it shows have elapsed in exactly one minute with no load on the generator. If it shows more than one minute,the governor is needing adjustment. By reducing the RPMs the voltage will drop as well.

[Roy1]

Most of the older Gas powered onans that I remember had adjustable carburetor linkage one adjustment for fine adjustment and one for more response. I guess a better id would be governer. Adjusting will change frequency as well as voltage. My older 6 kw unit idled at 130 volts and ran at 115 under full load with both airs on. If it were set to idle at 115 volts the full load volts would be too low Under load and I could only run 1 a/c unit. So for the 30 years I owned it I kept it at 130 idle and never had a problem. I’m sure the frequency was a little higher under no load.