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 D090241978Sorry about the length of this.Thanks!

Welcome to the Forum!You've done well describing symptoms and what you've done so far. AND, Most Importantly, Model and Spec! We had a lot of generator experts for awhile, but our members were vague in their descriptions and lacking in that Model/Spec info, to where many of those experts bailed.Do you have the Service Manual for this generator? We can probably help with at least that, then you can at least follow their troubleshooting flowchart.I do know that mud daubers and spiders love LPG. Look for webs, mud, and nests, especially around the regulator and carburetor areas. It's a long shot, but there might have been an insect obstruction and you broke it loose pulling the generator. I'd hate to see you heave it all back in only to find there was still a problem.If it's rich, and LPG pressure is a little high, sounds to me, NON Expert, that regulator setting could be an issue too.

Yes, I have the factory service and parts manuals for this unit. I have read about the problems with the demand regulator vent hose plugging by searching on this site, and this generator is new enough that it has the foam filter on the end of the vent hose. Because it has the filter, I did not check the hose for an obstruction.The parts that I think are most likely to cause this sort of problem are the demand regulator mounted on the unit and the carb, but the service manual says these two items rarely cause trouble. Here is what the service manual says about these two components.Demand RegulatorThe demand regulator assembly supplies fuel to thecarburetor. It is usually not the cause of fuel systemproblems. All other possible causes should bechecked out before adjusting or replacing the demandregulator assembly. Figure 8-24 illustratesthe regulator with priming solenoid used prior toSpec L on Model KV or Spec B on Model KVD. Thedemand regulator on later models does not have apriming solenoid.LPG Carburetor (Begin Spec E, Model KVand Spec A, Model KVD)See Figure 8-27. An LPG carburetor is not likely tocause problems and should be replaced only afterall other causes have been eliminated (see Section6. Troubleshooting). It is not necessary to adjust fuelmixture. These carburetors are calibrated at the factoryand the adjustments are sealed.The LP pressure reading I mentioned was a static reading as I did not have the correct fittings to tee it in so I could check pressure while the generator was running, I plan on getting the correct fittings to tee it in today and then I can see at what pressure the engine smooths out when I turn the tank valve towards shut off.Thanks!

I've had two starting/running problems with my Onan, vintage 2011. First was the oil level switch. With a full oil sump the gen. was running rough and was hard to start, then failed to run. Long story cut short, disconnected the oil level switch, gen. starts very quick and runs as smooth as new. Second problem, gen. would crank but not start. With the front access panel removed, the carb is in front of you, there was a small spring on top of the carb that was disconnected, hooked up spring and she fired right up.Possible oil leak could be the oil level switch. It screws into the sump. Location is to the right of the oil fill tube. On mine the wire to the switch is tie-wrapped to the oil fill tube. When the switch senses loss of oil level its contacts close grounding the circuit.Maybe this will help.

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.

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!

Onan 2500 KVD problems | Good Sam Community

j-d
Explorer II
Nov 22, 2016
pirlbeck wrote:
OK, I feel like a complete idiot.....

No, just an Honest Man!

Glad it's working!
pirlbeck
Explorer
Nov 22, 2016
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
Explorer
Nov 22, 2016
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
Explorer II
Nov 22, 2016
mine was air filter
j-d
Explorer II
Nov 22, 2016
Above Link as Clicky
pirlbeck
Explorer
Nov 22, 2016
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
Explorer
Nov 19, 2016
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
Explorer
Nov 19, 2016
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
Explorer
Nov 19, 2016
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
Explorer
Nov 19, 2016
Come over to Smokstak. We can help you.

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