|
|
West Central Iowa | New to me 2009 Onan RV QG 2500LP generator with 40 hours total run time starts very hard and runs rough.
I 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 different tank with a brand new regulator that I tested the pressure on with a manometer and while it is a little high at 13WC (service manual calls for 11WC), 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. Onan says carb is not adjustable and they offer no kits or parts for the carb at all.......only a new carb for $$$. 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
Thanks! |
|
| |
|
| I bought a Miller Bobcat LP welder/generator that ran the same way. Did everything you did checking regulator pressure and was within spec. But ran rich and loaded up on fuel.
Went ahead and chiseled the cover off the the supposedly non adjustable regulator and it turns out it was actually adjustable with a stupid tamper proof cover. Leaned the mixture out until it started missing, turnrned back in 1/2 turn richer and it now starts and runs like a striped......well you know!
Anyway adjust your regulator and it will likely be fine. If you can't adjust your regulator buy one for a turkey fryer as they are adjustable, fixed numerous gas grills simply by replacing the worthless non adjustable regulators. Same principal for your engine. |
|
| |
|
| Maybe something to check....
When I 1st got my Milbanks, when there was no or little load, like in test run mode, it would surge in RPM, like a lot,...... up, down, up, down.
After a lot of checking, it ended up factory forgot to install a small baffle between the engine and the outer case where the intake air was brought in. Anyhow what it did was mess up the sensor that read what the barometric pressure was, this controlled / changed the fuel regulator to the engine, thus changing the fuel mixture for it to run correctly.
It took me and the technician quite a while to figure it out.
Under full load, it ran like a dream.
Maybe you could have a faulty sensor ?? or connection ??? if so equipped.
Hope this helps.
Rog |
|
| |
|
Sac & Story county IA | The old standby line when forklifts don't run ---- "it's the regulator".
The parts for propane engine fuel systems are very generic. Most all run on liquid out of tank and vaporize to gas. Yours must run on vapor from tank? Is there a regulator? The carburetor is called mixer, so not much adjustment on that.
The fuel pressure-- they usually say 7 to 11 inches. Try to get closer to 7.
Regulator like this;
http://www.ebay.com/itm/ONAN-148-0311-LOW-PRESSURE-REGULATOR-NATURA...
The guy at Manilla that deals in forklifts has a good amount of parts and has been helpful when I have had propane engine trouble. |
|
| |
|
West Central Iowa | It is a total vapor system, no liquid is removed from the tank.The generator specs call for 11"WC for pressure, which is the same as all of the appliances run. The vapor comes out of the tank(S) to a combination regulator/tank auto switch valve. At the generator it goes into an electric fuel solenoid valve and then into a demand regulator and then into the mixer (carb). The demand regulator looks similar to the one you posted the link for, I would have to remove it to tell for sure.
The fuel pressure I posted was a static reading, I did not have the correct fittings to tee the manometer in last night. I plan on getting the fittings today and then I will be able to get a reading of the pressure running and when it starts to smooth out as I close the tank valve.
Good idea about the boys in Manilla, I bought a forklift from Jeff a number of years ago, but I never thought about giving him a call. He is a really good guy and I am sure he will probably be able to help me figure this out.
Thanks for all the help so far! |
|
| |
|
Sac & Story county IA | I have been known to use a clear plastic hose and water as a gauge. |
|
| |
|
West Central Iowa | E718 - 11/18/2016 08:10
I have been known to use a clear plastic hose and water as a gauge.
Yea, I built a U-Tube manometer with a clear plastic hose, a board and some clamps to mount the tube to the board. |
|
| |
|
central mich |
If the Impco or Maxitrol demand regulator is faulty it will be too rich on start up and if fact sometimes will not start at all. We do not work on small sets much. But the IMP52 matches to the Impco55 mixer, I am not sure of the Maxitrol
that might be equivalent but the Maxitrol ES402 (EV now I think) matches the Imp53. Both of which are prob to large for the small set. And remember the demand regulator has to be upside down with the spring removed with negative pressure at the mixer.
If it has excessive fuel all the time then I would lower the pressure down as 11"WC would be the max that we see.
We work on some 400kw natural gas black start gen sets which are in a facility with some NG 300 rpm engines that have the turbo chargers outside of the building and the turbos are about 8-10ft in diameter. |
|
| |
|
West Central Iowa | 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.
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 am going to try to post a picture of the demand regulator. I would really like to find a supplier for this part besides Onan as typically there parts are overpriced in my opinion.
Edited by pirlbeck 11/18/2016 21:09
 (IMG_1196A.jpg)
Attachments
----------------
 IMG_1196A.jpg (291KB - 200 downloads)
|
|
| |
|
central mich |
The carb or mixer does the fuel air ratio. We used to think that the Impco was simply an additional safety and have even removed them from the system but we would recommend that they be installed.
I just gave a 20kw to one of our employees. That unit had the Impco 55 mixer which has no diaphragm. With the Impco
52 removed it would load close to 20kw but it would not start with the auto start after three attempts it would fault out.
with excessive fuel.
And that was with 7" WC. With the Impco 52 in place it would only load about 10kw. So I gave him a new Maxitrol or Impco demand regulator and now it runs perfect, i.e it starts up fine and loads to about 19kw. So it is important to have the negative pressure on start up and that is recommended on all propane units on vapor.
The demand units seem simple but this unit was not working correctly.
Propane on vapor should be 1.5 " WC neg at the mixer or carb. |
|
| |
|
West Central Iowa | Jim, thanks for your help on this. 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 in not damaged in any way. I put it back together and reinstalled it and the engine runs exactly the same......way too rich.
I am going to pull the carb/mixer next and see it anything appears to be wrong with it. I am starting to wonder if this thing ever ran properly from new on.
Thanks again! |
|
| |
|
West Central Iowa | 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.
Thanks! |
|
| |
|
central mich | Call Dave or Phil at Carb and Turbo at 952-445-3910.
They are the official tech reps for Impco and are great guys. They will help you. |
|
| |
|
West Central Iowa | I will try to call them Monday morning.
Thanks a lot!!!! |
|
| |
|
West Central Iowa | I talked to Phil this morning and he gave me a couple more simple tests to do. After doing these tests he feels that the problem is most likely in the carb but he suggested trying 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!
Edited by pirlbeck 11/21/2016 13:50
|
|
| |
|
West Central Iowa | 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!!
|
|
| |
Propane generator running rich??
