Onan MicroQuiet 4000 crapped out while running

[DonTom]

One rod is moved by the thermal automatic choke, the other is moved by the governor to maintain engine speed, the springs are there to act as return tension.

I don't think we are talking about the same thing, so I took some photos. I am asking about the wire thin rod, which is really a spring on the very bottom of the three rods going to the carb.  Notice each end of the spring  connects to the EXACT same place as the rod. Not different at all, so we have a spring around a rod and so it cannot do anything at all, cannot return anything at all.


Is mine connected incorrectly?  I don't think I moved anything from the way it was to begin with.


See my photos below of each end of the spring going to each end of the SAME rod so it is impossible to return anything.

 

[Isaac-1]

Ah, I see your mistake now, the spring should be connected to the exposed end of the rod, not through the hole, this removes play that would be induced by the rob wobbling in the hole.

See correct placement photo below

 

[DonTom]

Ah, I see your mistake now, the spring should be connected to the exposed end of the rod, not through the hole, this removes play that would be induced by the rob wobbling in the hole.

See correct placement photo below

Thanks for that! Now I can see what it does, it is just to reduce the play on the rod going to the carb by putting a little inward pressure on the rod.


-Don-  Auburn, CA

 

[DonTom]

Since I had nothing planned for today, I removed the generator from my RV. Wasn't that tough of a job. I've done countless larger jobs.


My starter is an Onan Model 191-1798, which I just ordered a new on on Amazon which  should be here on Feb 17.


My old starter runs fine when no load, connected loose to my house battery. Sure has a lot of kick.  But I doubt that means anything.  The flywheel that the starter runs  moves freely and I can feel the compression, which seems normal. So I know my engine isn't frozen, but I am surprised the starter seemed so normal with no load.


Now I see the fan, just to the right of the fuel pump. So now I know where not to reach when it's running.


When I get the new starter, I will run the generator just  outside the RV to make the adjustments and such, if everything necessary will reach okay.  That should be easier to work on that way, with the cover off.


-Don-  Auburn, CA

 

[Isaac-1]

While you have it out, check the condition of the black rubber hose that runs across the top as it is a pain to change it out with the cover on.

 

[DonTom]

While you have it out, check the condition of the black rubber hose that runs across the top as it is a pain to change it out with the cover on.

It looks okay, but what does it do?


If we are talking about the same hose, it looks more like cheap plastic than rubber and doesn't connect to anything on either end.


-Don-  Auburn, CA

 

[Isaac-1]

I am talking about the one that is a breather tube that goes into the valve cover.

 

[JayArr]

Hey Don

Is there any way to take the rod from the new carb and use it to repair the old one?

Assuming the old carb is a genuine Onan it will be superior in quality to the new one, the jets should be accurate for that exact engine etc. etc.

The old carb ran the engine properly except for one minor flaw on the speed.

I think you would be better off using the cheap Chinese carb as a parts unit to repair the original.

 

[DonTom]

I am talking about the one that is a breather tube that goes into the valve cover.

Oh, I will take a good look at it in the morning. I will probably replace it regardless.  It is cheap enough.  But I cannot find it on Amazon or E-Bay.


BTW, do you have any idea what the other hose is for that goes over the top of the engine from rear to front, with no connection on either end? On the rear of the generator there is even a bracket to hold it in place.  But it holds it to nothing.


I can take a photo of it in the morning, on each end, if necessary.


-Don-  Auburn, CA

 

[DonTom]

Hey Don

Is there any way to take the rod from the new carb and use it to repair the old one?

Assuming the old carb is a genuine Onan it will be superior in quality to the new one, the jets should be accurate for that exact engine etc. etc.

The old carb ran the engine properly except for one minor flaw on the speed.

I think you would be better off using the cheap Chinese carb as a parts unit to repair the original.

No, it's not a replaceable part, besides, it looks better quality there on the cheap carb!


Nevertheless, If I decide it is a jetting  or some other carb problem, but not just a choke problem, I will buy a new Onan Carb for $305.00. There is an Onan dealer in Sparks, close to my Reno home. 


-Don-  Auburn, CA

 

[Tom55555]

No, it's not a replaceable part, besides, it looks better quality there on the cheap carb!


Nevertheless, If I decide it is a jetting  or some other carb problem, but not just a choke problem, I will buy a new Onan Carb for $305.00. There is an Onan dealer in Sparks, close to my Reno home. 


-Don-  Auburn, CA

I was looking at your bikes and a little surprised you haven't had a KLR650. Mine is a 2000. I updated the tires, seat and wind shield. Everything else is stock; runs two up off road great.

https://www.youtube.com/watch?v=YrxPPei9M0w

 

[DonTom]

It looks like I found my choke problem. The choke control thingy probably  isn't going to get warm enough to fully turn off the choke. Perhaps was less critical with the Onan carb than with the cheap carb, but certainly isn't right. See top photo below.


Below that I have a photo of the unknown hose that is not connected on either side, so I wonder what it is supposed to do.


-Don-  Auburn, CA

 

[Isaac-1]

I don't think  mine has a hose to nowhere, but I will check this afternoon and let you know.  As to the breather hose  here is a link to the ebay seller where I bought mine a couple of years ago, it looks like the price has went up a couple of dollars since I bought mine,  https://www.ebay.com/itm/Genuine-Onan-Cummins-123-1917-RV-Generator-Breather-Tube-Micro-Quiet-KY-/192370213592

 

[DonTom]

I don't think  mine has a hose to nowhere, but I will check this afternoon and let you know.  As to the breather hose  here is a link to the ebay seller where I bought mine a couple of years ago, it looks like the price has went up a couple of dollars since I bought mine,  https://www.ebay.com/itm/Genuine-Onan-Cummins-123-1917-RV-Generator-Breather-Tube-Micro-Quiet-KY-/192370213592

Thanks, I also found my choke heater tube there on E-Bay and have both on order.


-Don-  Auburn, CA

 

[Isaac-1]

Sorry got side tracked while I was at the RV today, will try to check when I am there tomorrow

 

[DonTom]

The switch appears to be a common Carling brand switch, you can probably get the model number off the back

I discovered that number on the switch only works for the switch, not the cover. The covers are custom made for Onan and other companies.


You can buy some of them as a complete unit on Amazon or Ebay.  But it sure helps to have the Onan part number first, as many look alike and they do not give much detail.


I finally,  after a lot of searching, found my switch to be  an Onan 308-1038 as a complete assembly. At around  ten times the price of only the switch.


-Don-  Auburn, CA

 

[DonTom]

Sorry got side tracked while I was at the RV today, will try to check when I am there tomorrow

Thanks.


BTW, do not try to remove that hose from the front. It will come out easily. But  you will never get it back under the rear bracket without removing the generator from the RV.


I wonder if it has something to do with the cooling. It sure looks like it cannot do much, no matter what it is designed to do. But I guess the engineers had a reason to put it there.


-Don-  Auburn, CA

 

[Isaac-1]

I checked my Onan KY 4000 and it does not have that hose to nowhere, of course if you have a different revision spec code it may be something they added

 

[DonTom]

I checked my Onan KY 4000 and it does not have that hose to nowhere, of course if you have a different revision spec code it may be something they added

Interesting. I just wonder what that hose does in mine.

Here is an update. Rain here has been slowing down much work on my generator, since I am working on it outside just under the RV. But what I recently discovered, is rather strange.

Since my old starter worked so well when connected direct to the house battery, with no trace of any issues, I decided to put it back in the generator again. It didn't seem to work inside the generator at all, no noise or anything this time. Not even a click from the solenoid.

So this time I did some testing.

First, I better explain this:

The generator mounts to the four sides. The ground wire from the RV also goes to the side. The bottom of the pan has a ground wire to the engine.

But there is high resistance between the bottom of the generator and its sides. Looking at the generator, it looks impossible for this to happen. But my analog voltmeter doesn't lie!

So what I did is ran my own cable from the engine to the side of the generator. Old starter is fine. No trace of any issues now when mounted inside the generator.

This means I never even had to take the generator out of the RV at all, I only needed to get a ground to the bottom of the generator plate.

Am I the first to have such a weird grounding issue? The smoke I was seeing when trying to use the starter must have been coming from between the sides and the bottom plate that the generator is mounted on.

I will take a photo later, to show where the ground issue is. It's almost unbelievable that there could be high resistance between the bottom plate and the side.

In other news, I received the new starter yesterday, But I see no reason to install it as the old starter is fine.

I didn't get a chance to reconnect everything and run it, (being sure the choke is open when warm) , because of rain. More rain is coming today also.

But I only need to connect the fuel line and other very minor work to test it. I just need to have a break in the rain. The rain will stop this afternoon, but come back tomorrow and after tomorrow, it is over with.

Perhaps I will get a chance to work on it this afternoon.

-Don- Auburn, CA

 

[Isaac-1]

You are not the first to deal with such issues, I spent a couple of days tracing problem on a home standby generator a year or so ago, turned out to be a bad battery cable, it looked ok on the outside, but was corroded inside the attachment lug. (confirmed by cutting it apart after it was replaced)