Generator putting out too much power

[swp5767]

Hello all! I have an Onan 4.9BFA 4000w gas generator. There is a plug on the cable the way it was sold to me. The PO used this for a race car trailer to power one AC unit and some lights. He said he had no issues.. I would have to say the lights must have been really bright.

Here are some pics of what I have..

Below is the reading while its running.


Here is where the other end of the wire is.



Here is the schematic of the model I have.



What im not sure is, is it hooked up correctly? I tried testing different points on that termimal block and I either got 0 volts or 148 volts. Nothing in between.

Any advice would be helpful.

[swp5767]

This is what did the trick. I removed tention from this spring till the voltage came down to 120VAC. With a hefty load on the unit, the power stays steady.



Thanks for all the help!!

[Handbasket]

SWP, get an Onan service manual (can be ordered online from Onan if nobody's got one). Read up on how your model regulated frequency & voltage, and make sure you adjust with the right screw.

Jim, "What you are experiencing is not a problem. It is an undocumented feature. Thank you for calling Microsoft."

[swp5767]

copeland343 wrote:
If meter is correct you will need to slow rpms down a little. Using the speed adjustment screw maybe a 1/16 of a turn.

There is only one screw to adjust, but when I back it out some, it does not make contact anymore nor does the RPM lower anymore.. I can physically push it till the screw makes contact again and the RPM is lower, but as soon as I let go, it goes back into place.

There must be more to that setting.. I don't see any kind of voltage regulator on this unit.

[swp5767]

enblethen wrote:
Have you checked the frequency?
Some change voltage and frequecncy as RPMs increase.

The voltage does lower when the RPM's lower. The one thing I cant test is the engine RPM. So I can get it down to 120 range, but the engine seems to be running too slow.

[copeland343]

If meter is correct you will need to slow rpms down a little. Using the speed adjustment screw maybe a 1/16 of a turn.

[swp5767]

After some more reading, these older Onans regulate power by engine RPM.

[dbbls]

I noticed the voltage on the Onan I had was high when there was not a load on it. The load lowered the RPM slightly.

[Hondavalk]

Not to ask the obvious but have you verified the meter on a known voltage source.

[enblethen]

Have you checked the frequency?
Some change voltage and frequecncy as RPMs increase.