Onan 4KY F series Gen Only runs while I hold the choke open

[bjhamlyn]

I know there are a million Onan posts out there, but I haven't found quite what I am looking for yet, so I figured i'd ask here.

I have an Onan 4KY F series generator with a little over 200 hours on it. The generator is in a motorhome that is new to me. The generator had not been started in several years. I checked it our, put in new batteries and checked the oil level then tried to start it. It started for a few seconds when I used starter fluid, but then shut off. I decided that I needed to remove the carb and clean it. I used a 1 gallon can of carb cleaner from advanced auto parts (the kind that you lover the parts into), and disassembled the card as far as possible then let it soak for about a half a day. I then drained the solvent out if it and cleaned it watch spray carb cleaner, then dried it with my compressor. Now the generator starts up, but will only keep running if I hold the choke all the way back (wide open). I have tried adjusting the main adjustment screw (altitude screw). I even removed the plastic limiter to adjust it several turns in each direction. Nothing seemed to help. I tried to remove the air cleaner to see if maybe it was restricting air flow. I noticed a slight difference, but it would still shut off as soon as I released the choke.
What is the problem? I just read something about the generator not running if the motorhome fuel level is below 1/4th of a tank. I think mine is right about 1/4th now. Could that be the problem? Is my carb probably still a little gummed up? Is it an electrical problem? Maybe the oil level switch went bad?
Thanks,
-Brandon

[bjhamlyn]

Great news! The second cleaning did the trick. I guess I just didn't soak it long enough. I soaked it this time for about 1 1/2 days, then cleaned it with carb spray, to include all of the little holes. I then blew it off with compressed air, to include all the little holes again. I put it back on the generator and it started right up. Then it shut down after a few minutes. Turns out I had to adjust the "altitude" screw. I tightened it up until the engine was about to stall, then backed it off a little until it was running pretty good. Then I put a load on it and let it run for about 40 minutes just to make sure everything was good. It was, and I left a happy man.
Thanks for all of the help everyone. Couldn't have fixed it without you all.

-Brandon

[PaulJ2]

bjhamlyn wrote:
The linkage was backwards. Didn't solve the issue though. That's why I decided to pull it again and clean it a bit more thoroughly than the first time. And I was wrong in my initial description. It turns out that I had to hold the choke closed, not open to keep it running. In other words, I had to richen the mixture. That's another reason for me to think that the carb needs a better cleaning. I plan to put it back in tomorrow morning and see how it works.

Ok that explains things a lot. I agree then that having to hold the choke closed means that there are passages/jet still clogged inside the carb.

[bjhamlyn]

The linkage was backwards. Didn't solve the issue though. That's why I decided to pull it again and clean it a bit more thoroughly than the first time. And I was wrong in my initial description. It turns out that I had to hold the choke closed, not open to keep it running. In other words, I had to richen the mixture. That's another reason for me to think that the carb needs a better cleaning. I plan to put it back in tomorrow morning and see how it works.

[PaulJ2]

TEXAS wrote:
If holding the choke open makes it run. There is nothing wrong but the choke. Linkage is most likely wrong. Easy to do on this model. If I remember correctly. The linkage should pull the choke open. Not push

I agree. If the choke is trying to close after the engine starts--THE LINKAGE IS BACKWARDS!!

[TEXAS]

I give up.

[bjhamlyn]

I pulled it out again today. Took it apart and its soaking in carb cleaner now. I'll put it back together Sunday and see how it works.

[TEXAS]

If holding the choke open makes it run. There is nothing wrong but the choke. Linkage is most likely wrong. Easy to do on this model. If I remember correctly. The linkage should pull the choke open. Not push

[64thunderbolt]

If you have to hold the choke open to keep it running the carb needs cleaned. Been there. Remove it take it apart. Put it in a coffee can cover with seafoam and let soak for a few days. Blow it out with compressed air and it should work fine. Did this on a spare carb I had and it has been running fine on my friends gen for a yr now. It was doing the same thing before I removed it. Seafoam is your friend. I use it every fillup. Best cleaner you can get. Better than $280 for a new carb.

[j-d]

Then I'm glad I shot that pic as close as I did. And that YOU paid better attention. I thought they were done the same... So GOOD on YOU.

I took pix before taking it apart because I'd been cautioned by others Here on This Priceless Forum! I mentioned that the way the throttle and choke are linked together on the carb itself, the carb can't just be slid sideways from between air filter housing and the manifold. One shutter is always extended past the gasket surface. A member suggested using a screwdriver to pry the filter housing forward using the filter fastener bracket. I modified the plan by turning the wingnut over to provide a straighter purchase and it came out like this

I removed one of the TORX screws that holds the housing in place to keep strain off the housing. It's a T-30, size courtesy of another Member HERE.
Next time I might dab a little paint on each link and the hole it goes into. Yes, I succeeded the first time. But I'm older now...

[bjhamlyn]

j-d,
Thanks for the reply and the pictures to compare with. It is the left one that I have to hold. The pictures aren't exactly the same though. It's hard to tell, but mine has the choke linkage rod going to the rear (far side) of the choke. I must have made that mistake when putting it back together. I'll try to put it back on the front side tomorrow to see if helps. Hopefully that's what it is and it was just my dumb mistake and not something more serious or expensive.

[j-d]

One of OP's Pix



Pic of my 4KY Spec K



Looks like the linkages are connected the same way. Given the motor ends are connected right, of course... Ours runs well connected as shown.

Let's make sure: It's the Choke, the shutter on the LEFT, that you have to hold open, correct?

Be careful, too: If you race the motor, above the 3600-RPM it runs at to generate 120VAC @ 60hZ, voltage can get dangerously high. For anything that's being powered by the genny, that is.

[bjhamlyn]

[img]http://s723.photobucket.com/user/bjhamlyn1/media/Image1_zps2a487cbd.jpg.html?filters[user]=142170510&filters[recent]=1&sort=1&o=1[/img]

[bjhamlyn]

TEXAS wrote:
If you are having to hold the choke open. Your choke is not working. Need to find out why.When you let go of the choke it will close flooding the engine.

That's exactly what I was thinking. As soon as I let go of the choke the throttle revs up for a second or two, then it cuts out. I figure that since it is only running with the choke wide open that means that I am getting too much fuel. Other than adjusting the main adjustment screw, what else can I do to lean out the fuel delivery?

The gas is good, I drove the rig from California to Colorado two weeks ago, and I filled the tank up today too, so I don't think that's it. The motorhome engine is running fine. SInce i filled the tank up today, so now it's full, the quarter tank shutoff is eliminated as a possibility. On the plus side gas dropped down to $2.02 per gallon today, so it hurt far less than a few weeks ago.

I added a few pictures to hopefully help with the trouble shooting.

Thanks again for all of the help.

-Brandon

http://s723.photobucket.com/user/bjhamlyn1/media/Image1_zps2a487cbd.jpg.html?filters[user]=142170510&filters[recent]=1&sort=1&o=1

[img]http://s723.photobucket.com/user/bjhamlyn1/media/Image_zps2db44a65.jpg.html?filters[user]=142170510&filters[recent]=1&sort=1&o=0[/img]

[fischer]

If you post a picture of carb and choke , someone might see the problem.