Onan 2800 Microlite Generator sustained running issue.

[Selkirkslim]

Greetings to all.
I'm a new person to the site and , like the rest of us, in need of some assistance.
The Onan Generator, 2800 micro lite I own, has a significant issue in that it will not continue to run , and run at a consistent RPM .

I have changed out the carburetor as per other suggestions ( I found the rebuild kit for this to be very spendy and a new carb to be alot less) , changed out the fuel filter ( in line) and replaced fuel hoses as I saw fit to do while I was in on this beast.
The fuel pump, "appears" to be providing the fuel flow as it does have a steady good flow when I had it disconnected from the carb and watched it.
The issue begins here: After starting it, it will run all by itself but will not maintain a consistent speed( rpm) and after a short period of time ( 5-7 minutes) it'll shut down all on it's own . A re-start will get it back up again and it will do the same thing repeatedly.
I've played with the altitude adjustment as best as I can and have noted even the slightest of adjustments will either create more of an issue ( it'll die shortly after an increase) or it'll continue to plod along at an unsteady RPM which, I know is not acceptable for AC power output.
This a a model number 2.8 KVFA26100E .

I'm fairly well versed in mechanic's and that sorta thing but this ones got me bothered.
The service manual, is of no help so I'm hoping someone else has had this issue and if so, what was done to correct it to run consistently and sustained.

I'd be most grateful and very appreciative of any assistance.

Thank you.

 

[DonTom]

I'm a new person to the site and , like the rest of us, in need of some assistance.
The Onan Generator, 2800 micro lite I own, has a significant issue in that it will not continue to run , and run at a consistent RPM .

I am not familiar with that model, but I will give it a try.

First, take the cover off the genny and see if there is a switch to start the generator. And then see if there is a red light on that switch.

If so, start the generator from there and let it run until it dies. That red light will then probably blink a few times. Ignore that but then press that switch one time to the left and then count the blinks. It will repeat. Say it blinks twice and then three times and keeps repeating. That is code 23. What you need to do is see what that code is and post it here.

See here.

-Don- Reno, NV

 

[Selkirkslim]

Thank you for your reply.

I've had the cover off of this ol bugger while I've been doing all of this . I've never caught a flash of any red light .

I've tried to upload a couple of photos and even after cropping them , the site won't accept tthem.

 

[DonTom]

I've had the cover off of this ol bugger while I've been doing all of this . I've never caught a flash of any red light .

Does it have the start/prime switch? Can you post a photo here of the front of the genny with the cover removed?

-Don- Reno, NV

 

[Selkirkslim]

Finally got it.

 

[DonTom]

Unfortunately, you don't seem to have that fault code light. That would make things a lot easier.

But you said the engine speed is staying the same. On the top of the carb, when running, is the linkage moving? If you can, take another photo so I can see the top of the carburetor.

If it is running at a steady speed, see if the control arm (governor arm) that the carb cables go to are moving during operation. That has to control the carb speed to keep the genny close to 3600 RPMs for 60 hz. If that is not moving, that is why your generator is running at a steady unknown speed, but probably not near the wanted 3600 RPMs and shuts down because of it.

-Don- Reno, NV

 

[Selkirkslim]

The issue begins here: After starting it, it will run all by itself but will not maintain a consistent speed( rpm) and after a short period of time ( 5-7 minutes) it'll shut down all on it's own . A re-start will get it back up again and it will do the same thing repeatedly.

It will not, maintain an even steady speed.
It surges up and down and will eventually shut off.

 

[DonTom]

It surges up and down and will eventually shut off.

It is supposed to surge up and down, so that much is good. Don't expect it to sound like a normal engine. The governor forces it to stay close to 3600 RPMS for your 60 hz. And that includes when the generator is ice cold or very hot. Unlike a car engine with the fast idle and all that.

Every 60 RPMs is one hz. So for 60 hz you need 3,600 RPM. If the generator cannot stay within around four hz of that frequency (56 to 64 hz) it will shut down. Likewise, too high or two low of a voltage will do the same.

Do you have a Killowatt meter or a thingy to measure the generator frequency and voltage? I have one of these.

When it runs, let's check the voltage and frequency. If they are off, the control board will shut it down.

Also see here:

-Don- Reno, NV

 

[Selkirkslim]

I'll know more about voltage/Hz output possibly tomorrow , Tuesday at the latest.
A Digital Volt Ohm meter is what I use and quite well versed in it.
As to the video clip and the oil dipstick, since this is on a 2800, I would think this wouldn't apply, though....

With a thorough search, I did find less than a hand full of complaints pointing towards the low oil pressure shut off switch being faulty.
That *Might* apply only if, that particular code was being displayed but , since there is no lamp, then I would think that's a moot point?

I have a new fuel pump coming and due in by Tuesday as the line of thinking I am on is, if the fuel pressure is not consistent , then that >could< have an effect on it.

The down side of the replacement carb is, it's not made by Onan....it's imported from China. Having read numerous reviews regarding that, and with no factory replacement available , a customer is left with no real recourse. Never did find the factory rebuild kit for the carb either so...

I'm at a loss.

 

[DonTom]

A Digital Volt Ohm meter is what I use and quite well versed in it.

Can it measure the frequency? I certainly would want to check that while it is running. Not many DVMs check frequency, but I realize some of the better ones can, such as many of the Flukes.

I am using one of those cheap carbs (<$40.00) and it works perfectly on my Onan 4kW. I gave it a five star review on Amazon. It couldn't work any better.

I am not sure which Onan's have the oil level issue. I also wonder if they know to screw in the dipstick all the way to check the oil level. I just don't know, but I think it is still something worth checking for any genny that stops intermittently.

If you see gas coming out of the carb line at a reasonable speed when you press prime, I doubt if you have a fuel pump problem. But if it is old, you probably want to change it anyway, as I did recently on my 4K.

-Don- Reno, NV

 

[jubileee]

I have two Onan 2800 micro lites. To get them both to run continuously, faultlessly, and smoothly, I had to move the fuel pump and suction fuel lines outside the generator box/ cover.
Too much heat for fuel lines/ fuel pump causing vapor lock. You can verify this problem by putting a piece of clear plastic gas line between carb and fuel filter and watch the vapor bubbles start in 5 to 20 minutes of running depending on ambient temperature.
By the way, I also moved the fuel filter outside the cover.

 

[Selkirkslim]

Yes sir. This DVOM measures the Hz and a few other wonderful tricks. Diode tester being one of them.

The 2800's to my knowledge do not suffer from the dip stick issue. I believe that is limited to the 4000 series.

We'll find out more in a couple of days on the fuel pump.

 

[Selkirkslim]

I have two Onan 2800 micro lites. To get them both to run continuously, faultlessly, and smoothly, I had to move the fuel pump and suction fuel lines outside the generator box/ cover.
Too much heat for fuel lines/ fuel pump causing vapor lock. You can verify this problem by putting a piece of clear plastic gas line between carb and fuel filter and watch the vapor bubbles start in 5 to 20 minutes of running depending on ambient temperature.
By the way, I also moved the fuel filter outside the cover.

I haven't given this any thought as to a complete re-arrangement on the fuel system. It makes sense just due to the small enclosed space.
However , the hard cover is off of this , as is the "soft " cover from over the muffler choke heater portion. I did not notice any change in the operation , or I should say, non-operation when I put the soft cover on the choke heater or took it off.

Since you had to relocate both the pump and the filter as well as the line, I would presume then that the 12 volt leads off of the pump would be lengthened as well. That's a non issue- plenty of wire and a soldering gun plus heat shrink.

Even with the new carb on this unit and making very small incremental changes on the altitude adjuster , it doesn't seem to want to settle down and run at one steady speed.
This line of action is the next course I may try just due to what Don above in this thread stated. Load the system with say....10 amp item? and allow it to run and then make the adjustment on the carb.

Where I'm physically at, ( Pasco WA ) we're not much over a thousand feet above sea level so I'm left wondering if you're closer to the truth than I care to admit AND the system should be at least half loaded.

I won't lay hands on this unit again until Tuesday afternoon , and with newly acquired clear fuel rated line test out your theory.
While this did come out of an RV, it will not be going back into one. This one , at 23 amps, would be fine for general purpose electrical needs while it's bigger counter part, a 6500 watt 30 amp unit will supply most of my electrical needs in a situation I am working as fast as I can , to resolve and prepare for .
The 6500 will be fun as it's sat for a while so I'm pretty sure of what has to be done to that, just to make it go.

 

[DonTom]

it doesn't seem to want to settle down and run at one steady speed.

You judge that by the frequency, not what the generator sounds like it is doing. Mine NEVER settles down. It is exactly 60hz (plus or minus 2 hz max) and working perfectly. I have ran mine for hours several times.

An inverter generator (not what we have) may stay at a steady speed as they can run at any frequency as it is all changed to DC and back to AC.

But our Onans need constant automatic adjustment to keep that speed very close to 3600 RPMS and it makes it sound like it is NOT steady as it is continually adjusting to keep it as close as possible to 3600 RPMS to get that 60 hz. IOW, when it tries do go faster than 3600 RPMS the governor arm lowers the RPM and vice versa. When it is running watch the top of your carburetor. That will explain why it SEEMS like it never settles down.

But the frequency meter will not lie. If it says 60HZ, ignore what it sounds like. That probably has nothing to do with why it is dying. But if it is 66 hz or 54 hz, you found your problem. And that will force a shutdown. It will NOT run when off frequency by that much. But it will start and run fine until it gets around 5 or six hz off frequency and then will shut down.

-Don- Reno, NV

 

[Archies1996]

Hello new to this site and I just searched “Microlite” and found this thread.

So my Microlite 2800 is about 15 years old but I run it all the time, tons of hours on it but I maintenance the heck out of it and that’s probably why it has lasted so long but recentry when I’m driving with it running and the ac is on or off even, it shuts off. It won’t start back up by the remote but it does when I hold the governor arm all the way wide open(I think open) and press start button at the generator.
This is a new issue I’ve been having the last 2 or 3 drives. Oil is clean and perfect at the full mark.
I was wondering about that video posted by dontom about the oil needing to be just above the fill line. Does that do the trick?
Anyone care to chime in?

Thank you

 

[Selkirkslim]

You judge that by the frequency, not what the generator sounds like it is doing. Mine NEVER settles down. It is exactly 60hz (plus or minus 2 hz max) and working perfectly. I have ran mine for hours several times.

An inverter generator (not what we have) may stay at a steady speed as they can run at any frequency as it is all changed to DC and back to AC.

But our Onans need constant automatic adjustment to keep that speed very close to 3600 RPMS and it makes it sound like it is NOT steady as it is continually adjusting to keep it as close as possible to 3600 RPMS to get that 60 hz. IOW, when it tries do go faster than 3600 RPMS the governor arm lowers the RPM and vice versa. When it is running watch the top of your carburetor. That will explain why it SEEMS like it never settles down.

But the frequency meter will not lie. If it says 60HZ, ignore what it sounds like. That probably has nothing to do with why it is dying. But if it is 66 hz or 54 hz, you found your problem. And that will force a shutdown. It will NOT run when off frequency by that much. But it will start and run fine until it gets around 5 or six hz off frequency and then will shut down.

-Don- Reno, NV

Been a while since I got back to you Don In Reno NV.

The two control rods I had mixed up was one of the issues with the sustained running problem.
I apparently didn't pay close enough attention when I had the carb off and replaced it.

I did end up taking it in to the Cummins dealer and had it back the following day .

According to the service report , the two rods were incorrectly placed and, the carb did need an adjustment.

The unit produces steady 59 Hz at 1800 RPM and 60 when loaded up so it's a win , in my view.

 

[Gary RV_Wizard]

If pushing the governor open gets it working, I think you can be pretty sure that oil level is NOT a problem. Sounds like a fuel flow issue to me, but I'm not at all familiar with the 2800 engine or its throttle controls.

 

[Selkirkslim]

Hello new to this site and I just searched “Microlite” and found this thread.

So my Microlite 2800 is about 15 years old but I run it all the time, tons of hours on it but I maintenance the heck out of it and that’s probably why it has lasted so long but recentry when I’m driving with it running and the ac is on or off even, it shuts off. It won’t start back up by the remote but it does when I hold the governor arm all the way wide open(I think open) and press start button at the generator.
This is a new issue I’ve been having the last 2 or 3 drives. Oil is clean and perfect at the full mark.
I was wondering about that video posted by dontom about the oil needing to be just above the fill line. Does that do the trick?
Anyone care to chime in?

Thank you

My first question would be, why are you running this thing while you're driving down the road?

The oil issue is NOT a maintenance item on the 2800's. That , is more likely to be seen on the 4000's.

I'll side with Gary, RV Wizard ; this is not an oil issue but more related to a fuel issue. Either fuel delivery or fuel consumption.

While the regular and periodic maintenance is always a good idea, this gives rise to a possible clogged jet issue in the carb itself. From the sounds of your description, and with regard to present day temps ( which are excessive ) possible vapor lock would be one avenue to explore. Cold wet rag wrapped around the fuel line portion going to the carb as the fuel is most likely already and prematurely in a vapor form before it reaches it's final destination point, at the cylinders.

 

[Archies1996]

Thanks for answering up guys, I appreciate it.
So I should of mentioned in my first post that this generator is on a food truck that powers two things really, the ac and a small freezer for ice cream.
So reading above, it sounds like oil level is not the issue.
Question... Could it be the fuel pump? Or does a fuel pump totally stop working when it's bad?
Another thing is I did not check the light codes the last times it shut off. Later today I am set to drive the truck and if it shuts off again, I will definitely check the light patterns and hopefully get to know which code it reads.

 

[Selkirkslim]

Thanks for answering up guys, I appreciate it.
So I should of mentioned in my first post that this generator is on a food truck that powers two things really, the ac and a small freezer for ice cream.
So reading above, it sounds like oil level is not the issue.
Question... Could it be the fuel pump? Or does a fuel pump totally stop working when it's bad?
Another thing is I did not check the light codes the last times it shut off. Later today I am set to drive the truck and if it shuts off again, I will definitely check the light patterns and hopefully get to know which code it reads.

The Onan 2800's do not have "light codes".
To verify that, remove the side panel cover and look.

Affirmative; the oil level, is NOT related to your issue. Bear in mind the 2800 can only push, at max, 27 amps , 20 safely and anything after that is just about exceeding the limit.

The fuel pump pressure on these is 3.5-5 lbs . You can make 3 lbs easy by have a fuel source about a foot or two above the carb and that's plenty. I know this because that's how I tested out the fuel pump on a 6500 I recently brought back to life.

AC with that small freezer might be pushing the limits.

Check your amp draw .

What's the spec code on your 2800?