Onan 2500 KVD problems

[pirlbeck]

New to me 2009 Lance 845 with an Onan RV QG 2500LP generator with 40 hours total run time starts very hard and runs rough. It also appears to have an engine oil leak. When we looked at this unit the owner said that he did not remember when the generator was last run, but after a lot of cranking he was able to get it to fire and keep running. I did notice at that time that it was not running smooth, but I thought it may improve with some run time. After I got the camper home I tried to get the generator running and while it finally fired after a lot of cranking, it would not stay running when the start switch was released. It acted the same when trying to start it from the remote panel and from the control panel on the generator itself.

Last night I pulled the generator out of the camper and tonight I hooked propane and a battery to it and fired it up. It started pretty quick and it kept running after the start switch was released. I am not sure what changed that it will now keep running.

I do now know that the rough running is being caused by too rich of fuel mixture because it will smooth out and run very smooth if I close the fuel tank valve until it is almost closed. The air filter looks like new and running it with no air filter makes no difference. I have it hooked up to a tank with a brand new regulator that I tested the pressure on with a manometer and while it is a little high at 13WC, it runs the very same as it did with the camper tanks and regulator. If this was a gas powered unit I would be looking for either a carb adjustment or a carb problem, but with propane I don't know. Anyone have any thoughts on this?

Also there is an oil leak somewhere on the bottom side of the engine.....any common areas to leak on these?

If it matters the Model number is 2.5KVD2089B Spec-B and the sn is D090241978

Sorry about the length of this.

Thanks!

[j-d]

pirlbeck wrote:
OK, I feel like a complete idiot.....

No, just an Honest Man!

Glad it's working!

[pirlbeck]

OK, I feel like a complete idiot..... I was looking through the parts book listing today getting ready to order a few small parts for this thing and I noticed that there was suppose to be a door over the air filter access hole. The air filter is in the cooling air flow on the discharge side. When I seen that door shown on the parts list I got to thinking that just maybe that could have something to do with my over rich mixture problem. I used some masking tape to seal the area off and fires it up and it runs perfect. Well evidently that door has to be there.

Live and learn I guess.

Thanks for all of the help!!

[pirlbeck]

As I stated in my original post:

"The air filter looks like new and running it with no air filter makes no difference."

So I am pretty sure the air filter is not the problem.

Thanks!

[tmartin000]

mine was air filter

[j-d]

Above Link as Clicky

[pirlbeck]

This morning I called Onan/Cummins customer support and had them check for TSB's for this problem on my model and S/N of generator and they could find none.

At the recomendation of a shop in the twin cities area that does a lot of propane work and sells lotos of kits and parts I did several more tests.
I tested the demand regulator by checking it for flow with the hose disconnected from the carb, some spit over the end of the hose and with the tank valve on and the fuel shut off solenoid energized and there is no flow.

Then I tried clamping down on the hose between the demand regulator and the carb, and I can make it run properly. This supplier in the twin cities offers an adjustable flow outlet fitting for the demand regulator. Here is a link to this part.

https://carbturbo.com/product/33-ea-fitting/

While this may not be a "by the book" repair, I think it makes the most sense to try this next. My only concern with this fix is if the mixture will be close enough at all loads. The tech person at this supplier said this fitting is made for this purpose and felt it would be fine.

I will report back once I get this fitting installed and do some test runs.

Thanks!

[pirlbeck]

marcsbigfoot20b27 wrote:

pirlbeck wrote:

marcsbigfoot20b27 wrote:
I have a 2500 LP Onan also (Year 2000, maybe spec K?). 6 months ago it was hard to start, was surging badly at no load and had trouble managing a sudden load.

Found by spraying carb clean on the air filter that it was running lean.....idle would smooth right out.

Ended up yanking the demand regulator, getting a rebuild kit on Amazon for ~$60 and using only the diaphragm.

Now it idles normal and runs perfect under load or not.

Would you have a part number of the kit you bought? How were you able to determine that it was the correct kit for your generator?

Thanks!

Mine had a Garretson SD regulator with electric prime. It is possible the prime adjustment knob is in too far causing rich mixture.


The reg itself is also adjustable, the spring tension.....yours could be weak.
Impco regulator kit

No primer button on my regulator, also no adjustments anywhere on the regulator and the only adjustment screw on the carb/mixer is the idle stop screw.

[marcsbigfoot20b]

pirlbeck wrote:

marcsbigfoot20b27 wrote:
I have a 2500 LP Onan also (Year 2000, maybe spec K?). 6 months ago it was hard to start, was surging badly at no load and had trouble managing a sudden load.

Found by spraying carb clean on the air filter that it was running lean.....idle would smooth right out.

Ended up yanking the demand regulator, getting a rebuild kit on Amazon for ~$60 and using only the diaphragm.

Now it idles normal and runs perfect under load or not.

Would you have a part number of the kit you bought? How were you able to determine that it was the correct kit for your generator?

Thanks!

Mine had a Garretson SD regulator with electric prime. It is possible the prime adjustment knob is in too far causing rich mixture.


The reg itself is also adjustable, the spring tension.....yours could be weak.
Impco regulator kit

[pirlbeck]

TEXAS wrote:
Come over to Smokstak. We can help you.

I thought about doing just that......in searching for answers I was taken to that site number of times.

I will have to get signed up. What area would be best to post this problem in?

Thanks!

[TEXAS]

Come over to Smokstak. We can help you.

[pirlbeck]

I pulled the demand regulator this morning and took it apart and everything looks like new in it. The needle valve seems to seal fine and the diaphragm is very flexible and it is not damaged in any way. I put it back together and reinstalled it and the engine runs exactly the same......way too rich.

Next, I pulled the carb/mixer off and used carb cleaner and a blow gun on any open passageways and orifices. Not really anything that comes apart, so I could not do much other then that. I also checked/adjusted the valve lash.......and it still runs the same. Turn the tank valve almost off and it smooths right out. Also tried a regulator I could take a cap off and adjust the pressure. I adjusted it down to 10"WC (static) and still the same thing.

Looking like I am just going to start throwing parts/money at it. Searching online, it looks like a new carb/mixer is going to run $450.00 or more. A demand regulator would be $150.00-200.00. I can't see where there is anything wrong with the demand regulator, but you never know and it is cheaper, so maybe start there.

I hate just throwing parts at something and hoping it fixes it......but I don't know what else to try. Maybe on Monday I can get ahold of someone from Onan/Cummins and see if there are any TSB's or known problems that would cause this.

Anyone here that could give me some guidance or know of someone I could talk to?

Thanks!

[pirlbeck]

OK I got the manometer tee'd in to do some more checks.

Static pressure with tank valve on and engine off it is close to 16"WC. Seems hi to me, but this is a regulator I am using just for testing. I will check pressure of the camper system when I re-install the generator.

Engine running with tank valve all the way open it is down to 8"WC, which seems low but that may be due to how rich the engine is running so it is drawing a lot more fuel then normal.

When I start shutting down the tank valve it starts to really smooth out close to 0"WC and it actually runs the best a negative 1/2" WC. Am I correct in thinking it must be the demand regulator? I am not sure how this system works, as I have never messed with LP fuel systems, but everyone in the trade refers to what I would normally call the carb as the "mixer", so I take that to mean it does not meter the fuel at all, it just mixes it. That leaves the demand regulator to determine fuel mixture or "demand"

I would really like to find a supplier for this part besides Onan as typically there parts are overpriced in my opinion.

Thanks!

[pirlbeck]

marcsbigfoot20b27 wrote:
I have a 2500 LP Onan also (Year 2000, maybe spec K?). 6 months ago it was hard to start, was surging badly at no load and had trouble managing a sudden load.

Found by spraying carb clean on the air filter that it was running lean.....idle would smooth right out.

Ended up yanking the demand regulator, getting a rebuild kit on Amazon for ~$60 and using only the diaphragm.

Now it idles normal and runs perfect under load or not.

Would you have a part number of the kit you bought? How were you able to determine that it was the correct kit for your generator?

Thanks!

[marcsbigfoot20b]

I have a 2500 LP Onan also (Year 2000, maybe spec K?). 6 months ago it was hard to start, was surging badly at no load and had trouble managing a sudden load.

Found by spraying carb clean on the air filter that it was running lean.....idle would smooth right out.

Ended up yanking the demand regulator, getting a rebuild kit on Amazon for ~$60 and using only the diaphragm.

Now it idles normal and runs perfect under load or not.