Onan 2.8 KV Governor Settings

[Bnova]

Good morning all, I've only had a couple of opportunities to play with the new Minnie Winnie, so I'm not too familiar yet with everything, but getting there a little at a time.

I'm wondering if someone has messed with the gen gov settings.  It seems that the gov works, but not when you need it.  What I mean by that is the gen starts up and this is also something I've wondered about, it goes right to the throttle stop right away.  With it like that, it seems the gov would not be able to compensate for any load.  And this is evident when I run the microwave, the gen slows down significantly.  When I turn on the roof air it will kill the gen.

I can tell that the gov works by the surging that happens when I adjust the main mixture screw clockwise to the stop, it will start to surge and then smooths out nice when I rotate mix counterclockwise.

I wouldn't suspect any carb issues and this point, as it starts and runs very nicely, even with the gov not compensating when I run the microwave it doesn't cough or miss fire, it just gets pulled down in rpm.

Shouldn't the gov setting at no load be such that it will run somewhere off of the throttle stop screw?  Allowing some head room to increase throttle setting when it gets loaded down?

If I remember correctly, I believe the throttle stop screw is screwed in almost all the way.

[Bnova]

Alright, I had a chance to run up quick to my storage unit and take another look at things after doing some more research.  And I realize my earlier confusion with the throttle stop, that apparently is the idle speed stop.

When I turned the main mix screw counter clockwise that increased the rpm and stopped the surging.  But if I try to manually open the throttle the engine wants to die, it runs perfectly smooth in a no load condition, and then if I move the main mix screw clockwise the rpm slows down but then the surging starts.

As I mentioned in the first post, with the main mix turned CCW it can handle the micro wave running, but it pulls the rpm down quite a bit and there's no surging and it runs nice and stable and smooth.  But after more pondering, I'm wondering if maybe I do have a carb problem. 

When the main mix is CCW and the eng is turning really fast rpm and the throttle is still on the idle stop, is it in a constant overspeed condition and the gov is trying to idle it down but can't because it's already back at the throttle stop screw.  Which by the way is turned almost all the way in.

Then when I turn the mix CW the eng rpm slows down and begins a pretty steady surging condition.  I didn't load it down while it was surging ever just because I thought it sounded my nicer with the main mix turn the other way.

[pvoth1111]

be care when adjusting.....changing the HZ by increasing the speed can destroy today electronics....

adjust the HZ and then you adjust the Volts while keeping the HZ at 60....the genny will/should adjust itself after that if the voltage regulator and else are in working order....there should be a procedure in the manual.....I have like 4-5 adjustments to make on mine and it takes time to get it right.

[Bnova]

Thanks pvoth, hopefully I'll get a chance next weekend to make some more observations and adjustments.  Might just pull the float bowl too, this thing only has about 75 hours on it so given it's age, it may have a bunch of crap in passages, but I still say it runs really nice.  Well I guess we'll see next chance I get to play with it.

[pvoth1111]

get a meter that measures HZ....you cant guess....any adjustment that makes the revs go up or down changes the HZ (hertz) also called frequency it has to be at 60 in the us and 50 in Europe..... I use a fluke 87 series.....pricey but worth it to me....

[Bnova]

Yeeha!  Just needed to clean the carb and the gen runs nice and solid.  Not the easiest thing to get the carb off but it's do able without removing and unboxing the gen.

[Oz]

    

[bluebird]

Be very careful adjusting on that generator. It must run at 3600 rpm to achieve 60 hrz. If you overload it very many times you're taking a chance of burning up the regulator or the windings in the stator or both. With that 2.8 you won't be able to run everything at once. After you get the rpm set right again, and you can do this by check the hrz with a meter, needs to be 60 to 62 hrz unloaded. If the generator starts  to stumble when applying a load you are probably over loading it. How many amps is that 2.8 rated for? Should say on the data plate, try not to over load it, those onan electronic regulators are pricey. 

[eXodus]

be care when adjusting.....changing the HZ by increasing the speed can destroy today electronics....

that's not true, it destroys modern CHEAP electronics.  If you get something high quality it can use anything between 90V and 250v and between 40hz and 70hz.
But it also destroys old cheap electronics.


As always if you got something sensitive get a good pure sine wave converter.

[Bnova]

Hey thanks for all the helpful advice guys, I do appriciate it.  I have a nice little meter that plugs into a 110 outlet so I can monitor the volts and fregs continuously.

When I first fired her up after reinstalling the carb she was running pretty fast, 130 volts and 70 freqs.  Got her dialed back to 120 something and 60 freqs, then went to adjusting the idle and main mixutures.  After getting the mixes set properly I went back to the gov and set up the volts and freqs.  The service manual explains the process quite well, I followed the instructions and it all worked out.  She ran nice and steady under heavy load as well as in the no load condition.

And being such a small gen, 2800 watts and 23.3 amps, I do realize that I won't be able to run much else while the roof ac is going.

I ran the gen with the roof ac going for about an hour and no problems so I think she's good to go.  I've got this 4000 mile trip to do right out of the gate come mid may so I need to be sure everything is up to snuff before then and little by little we're getting there.  Thanks again for the friendly advice.

[bluebird]

When I had a 4000 I couldn't run the ac, coffee pot, and micro at the same time. I usually would turn the compressor off on the ac while doing breakfast.  Good luck on your trip.

[Bnova]

Thanks Blue.

[75Travco]

Sounds like you have the generator working good.  The Onan has two governor adjustments - speed, and sensitivity.  The first time I ran my 6.5NH, it was putting out around 200 volts / 100 Hz!  Backing way off on the speed adjustment (reducing spring tension) got the voltage down to 120.  It was real quiet and smooth at the requisite 1800 rpm.

At this point the generator surged during loading and unloading.  I cleaned the carburetor several times, and replaced points and plugs, but the surging continued.  Finally noticed that the sensitivity adjustment was set all way to one side.  Moved the adjustment to the midpoint, and the old Onan worked perfect.

[Bnova]

Nice, you gotta love it when it's an easy fix.  I'm still making minor adjustments to the automatic choke to fine tune it.