Onan Micro Quite Generator Issues

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sortiz627

Member
Joined
Aug 28, 2020
Posts
8
Howdy all! I am having issues with my Onan 4000 MicroQuiet Generator and am hoping for some help. I will provide as much information as possible to help troubleshoot the issue but please let me know if you need anything else. I can provide pictures or videos if needed, as this issue is driving me crazy.

Model - 4KYFA26100K

This unit is in my in-laws RV and the RV had sat for a few years without it being exercised but late last year we convinced them to let us get the RV running so we could all enjoy it. Its a 2005 Winnebago with 10K miles on the engine and only 110 hours on the generator. On the generator, I replaced the carb, spark plug, oil, air fiter, and got it running in October of 2019. Each month we either used the RV for short trips or I would go to the storage facility each week, fire it up (RV and Genny) to keep things fresh/charged.

We went on a long distance trip two weeks ago and the Genny ran fine until we got to higher altitude when I had to make an adjustment to the altitude knob. It ran for a while but eventually stopped and since we were on shore power, it wasn't the end of the world.  Got it back home, went through it again and got it running by changing the fuel filter. Last weekend, as I went to fire it up it would crank, start and shut down within 10 seconds. I did some troubleshooting while it was still in the RV, and then decided to take it out to check all wiring and do a full service review.

While having it out, I have completed the following;

- Replaced fuel filter
- Cleaned spark plug
- Cleaned Magneto (it was dirty)
- Cleaned Ignition coil (dirty too)
- Cleaned Slip Rings (with Commstone)
- Cleaned Brushes (with scotch bright pad)
- Carb was replaced in October 2019, but still removed it, checked it, no gummy gas/bad gas, still cleaned it)
- Tested Fuel Pump (works fine, with good pressure)
- Tested spark plug (strong spark, enough to shock me  :eek: )
- Adjusted choke
- Checked continuity to all wiring
- Compression check was at 135 PSI

I am attempting to bench start the unit in my garage and have a Optima Yellow top battery and have my battery charger connected for good measure.

The generator will crank, fuel pump, pumps, spark, sparks, carb does allow fuel into the carb throat, but still nothing. I will say that it is sometimes hard to crank but it does crank once the voltage is sufficient from the battery and battery charger.

At this point, its been a week of me reading forums, troubleshooting, going through the service manual multiple times and I still cant get the darn thing to fire over to then address the original issue of it shutting off.

Anyone have any suggestions on next steps?

FYI, I have a few things coming in the next week to replace and try (ignition coil, spark plug) but wanted to see if anyone could help in the meantime as I think it is something easy but fear it could be the control board.
 
It sure sounds like you've covered all the bases.  The only thing I can think of is to rebuild/replace the carb.  Also, check the fuel hoses for brittleness or leaks that could possibly introduce air and cause vapor locks.  Hoses are cheap to replace anyway.

I'm no expert and I'm kinda brainstorming with you.  Usually, changing the fuel filter does the trick for me..but you've done that already.

Also check this thread on this forum.

http://www.rvforum.net/SMF_forum/index.php/topic,85869.0.html
 
davismills said:
It sure sounds like you've covered all the bases.  The only thing I can think of is to rebuild/replace the carb.  Also, check the fuel hoses for brittleness or leaks that could possibly introduce air and cause vapor locks.  Hoses are cheap to replace anyway.

I'm no expert and I'm kinda brainstorming with you.  Usually, changing the fuel filter does the trick for me..but you've done that already.

Also check this thread on this forum.

http://www.rvforum.net/SMF_forum/index.php/topic,85869.0.html
Click to expand...

Thanks, I may have to go that route to check off anything I can to get it running again.
 
Replace the spark plug with a new one. They are cheap $5. You can also pull the plug that is in there, reconnect it back onto the plug wire and ground it to some metal while turning it over to see if and how well it is sparking. DO NOT do this bare handed or you probably will get the ZAP of a lifetime. Wear a heavy glove to insulate your body from the electricity. Plugs foul easily in bad mixtures and it sounds like you encountered a bad mix in higher elevation. Best to replace. If you do the spark test and it sparks, replace it anyways.



There are fault codes that you can retrieve from the unit. There is a section in the owners manual and the service manual to retrieve codes. You should be using the cummins/onan setvice manual.
 
When you say the spark sparks, did you observe this by holding the plug against the case?  (Of course, even with that test a plug sometimes won't fire under compression so it's not an absolute test.)  Just seems like if you have spark, you ought to at least get a "pop" .... say with the air filter removed and some start fluid sprayed in.  The new plug you have coming may just do the trick.

I had a hard-start problem on mine and the spark at the plug was very anemic to almost non-existent.  Finally degraded to a no-spark/no start so I did a "field expedient" in order to save a vacation trip by gapping a new plug down to about .015 ..... and that gave me back a (very weak) spark.  Ran for a time but eventually went to no start.  I felt it just HAD to be the mag assy.  Too tough for me to remove the unit so I paid Cummins to install a new mag.  That was several years and about a hundred hours of run-time ago.  BTW- mine is a Spec K; the mag is all potted in one assembly so a little different than yours.

Don't know if my experience helps at all..........just data I wanted to share.

Good luck with the fix.  Please let us know the outcome; these Onan's can sure drive ya nuts.

Be safe.

BTW-2  Henry posted while I was typing so some of the above is redundant.  But some of the above may be of interest.






 
Henry J Fate said:
Replace the spark plug with a new one. They are cheap $5. You can also pull the plug that is in there, reconnect it back onto the plug wire and ground it to some metal while turning it over to see if and how well it is sparking. DO NOT do this bare handed or you probably will get the ZAP of a lifetime. Wear a heavy glove to insulate your body from the electricity. Plugs foul easily in bad mixtures and it sounds like you encountered a bad mix in higher elevation. Best to replace. If you do the spark test and it sparks, replace it anyways.



There are fault codes that you can retrieve from the unit. There is a section in the owners manual and the service manual to retrieve codes. You should be using the cummins/onan setvice manual.
Click to expand...

I have one coming in a few days, but may just go scoop one up so I can test it this afternoon.

Interesting part is, I have no error codes being thrown while bench starting it. I was getting codes historically but now when it cranks, it doesn't throw a code.
 
youracman said:
When you say the spark sparks, did you observe this by holding the plug against the case?  (Of course, even with that test a plug sometimes won't fire under compression so it's not an absolute test.)  Just seems like if you have spark, you ought to at least get a "pop" .... say with the air filter removed and some start fluid sprayed in.  The new plug you have coming may just do the trick.

I had a hard-start problem on mine and the spark at the plug was very anemic to almost non-existent.  Finally degraded to a no-spark/no start so I did a "field expedient" in order to save a vacation trip by gapping a new plug down to about .015 ..... and that gave me back a (very weak) spark.  Ran for a time but eventually went to no start.  I felt it just HAD to be the mag assy.  Too tough for me to remove the unit so I paid Cummins to install a new mag.  That was several years and about a hundred hours of run-time ago.  BTW- mine is a Spec K; the mag is all potted in one assembly so a little different than yours.

Don't know if my experience helps at all..........just data I wanted to share.

Good luck with the fix.  Please let us know the outcome; these Onan's can sure drive ya nuts.

Be safe.

BTW-2  Henry posted while I was typing so some of the above is redundant.  But some of the above may be of interest.
Click to expand...

Yes I did hold it against the case to see if it sparked. I have tested it with a screwdriver in the spark plug boot against the frame and with the actual spark plug in the boot against the case. In both cases, it sparks and seems to be pretty strong.

I will try using some starter fluid, the gap is at .025 per the manual req and a new plug may be the trick.
 
Thanks for the suggestions team! If anyone else has any ideas, please post them.

Once I get this thing running, I will report back so future generations will have an answer!  ;D
 
Isaac-1 said:
My only other thought is timing or valve lash
Click to expand...

Good points.

I checked valve lash and it was in spec.

Timing, other than making sure the key is installed correctly for the flywheel, is there anything else that can be adjusted?
 
Nothing that I know of, though I did see where some guy was experiencing similar issues, and the key was bent allowing the timing to be far enough off that it would not start.
 
Fortunately it was just the spark plug and once I replaced it, I was able to get it started.

The original issue (wont stay running) after completing all of the other previously mentioned service, was due to the choke and governor needing adjustment.

All is good now, and I appreciate everyone's help!
 
Good news and glad its up and running.

Fyi... I have made several adjustments to the speed setting and the governor over the last couple years. I do not have a frequency meter to get the speed correct so I use a volt meter and shoot for about 122 volts under no load. I then make the adjustment to the governor to hold the speed setting and reduce the droop. So far I have been successful in keeping it within a range that provides decent power. For some reason these adjustments need to be adjusted. The governor has a spring so that is understandable but the speed adjustment is the adjustment that isn't something that will change. I suspect its a combination of alot of things like fuel, valves, compression and so on.

Some day I plan to get a frequency meter to see where I am at but I do not worry about it because the computer keeps track of the frequency and will shut the unit down if it is to high or to low. Does the same with the voltage.

Some things to remember is that you do not want to run the generator under no load so when your air conditioning shuts down, there needs to be some load remaining for the generator. This will affect how long and how healthy your plug will live. I usually use the fridge/converter for supplemental loads. I do not have an energy management system so I am on my own when it comes to load management.

After a few hours of running the generator under a good load, pull the plug and have a look at it. The plug will give you a pretty good look at how the generator is firing and how long the plug can go inbetween service.

The air filter is another element to the combustion health. The filters run about $15-$20 and its difficult to determine when a change is needed so I fabricated a thin foam covering that slips over the filter and collects the debris before it gets to the filter. It works great but requires strict regular maintenance which I welcome. It also allows the application of foam filter spay additive that is good to use is dusty environments. The filter has over 300 hours on it and it is as clean as it was when new. It is a little discolored but completely clean.

Here in Florida the temps are horrible all day and all night. I service the generator every 50-75 hours during summer months. Sometimes under 50 depending on what I am doing. Oil, filter clean and plug clean/replace.

One last thing.... Rodents love to climb up on top of the microquiet through the exhaust area and the air intake area. I fabricated screens for both areas after evicting a wood rat family that decided to make the microquit their home base. Chewed up a bunch of wires too. Had to take the genset out to repair. I dont plan on going through that again. If you do install protective screens (I reccomend it) be aware that it will restrict the cooling air some. Colder temps probably ok but warmer temps you might want to remove them.

Good luck.
 
sortiz627 said:
Fortunately it was just the spark plug and once I replaced it, I was able to get it started.

The original issue (wont stay running) after completing all of the other previously mentioned service, was due to the choke and governor needing adjustment.

All is good now, and I appreciate everyone's help!
Click to expand...

Good reason to always do &/or check the easy things first. Atleast now you are very familiar with the entire generator.
Glad it's now running good.
 
I will echo the thoughts of the board of Keep It Simple Stupid (KISS) Principle when it comes to these small engines. 

The small engine problems can be maddening for sure.

Also, have a can of starting fluid near by. 

John
 
Monday my Onan was throwing error code 47 (Ignition) it would start but each time it ran for less and less time.... Finally I gave up. went to supper. came back (It cooled off some in the interm) and it ran for several hours till I hit the STOP button.
And the next day all day till they finished the job and found my keys and I hit the Stop button
And last night for several hours
And this morning
No problem

I did add some oil after the 2nd stop but that was not it.  (IT was down about a pint)

And It was somewaht hot but not that hot

But why would a 47 Code just flat go away?

IN any case.. Rig is not long for my life due to being totaled so I'm not going to worry about it. 
 
JFDetroit,

Totaled?  I remember you saying something about a date with a body shop.  What are you getting next? and what happened was this the side swipe at the truck stop?

John
 
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