LP Generator problem

[Olefrank]

I have a 1997 Monaco Windsor motorhome that came with an Onan Marquis 6500 LP generator. It was plumbed into the LP tank via the "vapor" outlet. The book said to hook it to the "liquid" outlet. It wasn't running correctly so I took the coach to Camping World and after 4 weeks they said they had to change the connection to the tank, replace the regulator and some other gizmo connected to the regulator. Now it runs fine but stinks. I have used many LP machines and none of them run making that stink. What's up? Any ideas? I'd appreciate some help here. Feel free to contact me at atlasven@comcast.net.
Thank you in advance.

[Theberrys]

We have a 6.5KW Generac LP genny and it's run from a second regulator on the tank. I'd get some soppy water and look for leaks all along the line. Camping World has been known to make mistakes. Is your LP sensor up to date and working? About 5 to 6 years is all there good for.

If all else fails, take it to a LP repair man with some experience. This very well may not be something to trifle with.

Good Luck and be safe.

Dick

[Mike Canter]

I guess you need to define more about it "stinks". Yes the exhaust from a car or generator running on LP will stink. Is it the exhaust you are talking about or is it raw LP that you say that stinks?

[Olefrank]

It is the exhaust that smells bad. I believe that the mixture burned is inappropriate. I know there is a slight smell when you turn on a burner and it burns with too much or too little oxygen but this is a strong, heavy smell, not raw LP gas, but burned exhaust. I don't know how else to describe it. I'd sure like to know where else to take this other than Camping World or Cummins, as both don't seem to have a good handle on how to repair this. I guess LP run gennies aren't to common. I live in the greater Portland, Oregon area.
Thanks for the reply.

[jimkate]

I also have the same generator. We complain of the same problem, often wonder if there's something wrong, or if it's safe to keep running the generator.

Also, we can't run both air conditioners with the generator. It doesn't seem to have enough power. Our coach has two 13,500BTU air conditioners.

Is this normal?

[97windsor]

We have the same unit, a 6500 LP Onan in a 97 Windsor. It will not run both A/C units at the same time. We used it over Labor day, 1 A/C unit and everything else electric including water htr, lights, microwave. It ran 24hrs and it used about 1/2 tank of propane. Ours does have a different smell to the exhaust but not a very strong smell. The amount of propane useage will tell if it is running to rich. Have you used it any length of time to see how much propane it used?

[Diplomat Don]

Olefrank....I don't know much about propane generators, but here are a couple of things that came to mind when I read this. If it was originally hooked up wrong and was possibly starving for fuel, could it be that it was adjusted/tuned that way and now doesn't like the amount of fuel it's getting now.

I would do as some others alluded to.....fill the tank (same weather and same time of day) and run the generator for three hours under load and then refill the tank. You'll now have an idea of how much LP you're burning per hour. This would be a good starting point for a technician to know if it's running rich.

I would look for one of the Cummins/Onans repair facilities that specializes in Onan repairs to check it out. Even if you located the best CW in the US, they're not set up for what you need checked/adjusted.

[Mike Canter]

I had a Generac LP gen on my last MH and the exhaust did smell. If the wind was correct then I had to shut some windows. My generator could power the two airconditioners all day long. There is only a couple of adjustments that pertain to the LP. One is the regulator pressure and the other is a double screw adjustment on the line that runs from the regulator to the carb. One of those adjustments (the smaller screw) is the run mixture and the procedure is simple for adjusting that. You just turn it one way or the other until it runs smooth. The regulator would need to be adjusted by an LP expert. If you plug a volt meter into the generator and it is right at 120 volts with one airconditioner on then all is great on the voltage. If it drops down then the regulator needs adjusting which is a small screw on a circuit board under the plastic cover. It should be able to hold at leat 117-118 volts with two airconditioners online. You can find the shop manual and operators manuals online if you do a search using your model number.

When I was stationed in Japan and was going to work in the morning on my bike if I got behind a taxicab that ran on propane then sometimes it would make me throwup especially if hungover. They are going to smell.

I sure find it hard to believe that the generator was hooked up to the wrong fitting on the LP tank from the factory. My tank had two main outlets on it. One went to the inside of the MH and the other went to the generator. Each one had the same fitting and same shutoff valve.

[jimkate]

Well Mike, I think you've just told me what's wrong with my generator. When it's running, the voltage is at 110V to 115V. Never higher, and constantly fluctuating, or pulsing from 110V - 115V. So, it appears that some adjustments are needed.

[Mike Canter]

Jim if it is under a 50% load it should not be pulsating. There are actually two adjustment. The generator speed (rpm) has to be set so you have 60hz power. You need some kind of frequency counter to do that and the other adjustment is voltage which is a small adjusting screw on the regulator printed circuit board. The RPM should be fairly stable. That small mixture adjustment being out can cause it to be unstable or a problem with the governor on the motor can be bad or have dirt, bugs or something jammed in it.

[Mike Canter]

I just found the Technical Manual for the NP Series Generac generator on my computer. It is in .pdf format. If anyone wants a copy the email me at mike.c@mindspring.com and I will email you a copy. It is a 1744 KB file size

[KIX]

Your gen exhaust smells because you are drawing liquid from the bottom of the tank rather than vapor from the top. Ethyl mercaptan, the odorant in propane, is concentrated at the bottom of a propane tank.
A propane tank's withdrawal fittings are labeled as "liquid" if there is an internal tube going to the bottom of the tank and "vapor" if the fitting communicates with the vapor space inside the tank.
A LP gas fueled engine runs on vapor and NOT on liquid. If liquid is supplied to the engine the liquid is vaporized before entering the carb. If vapor is supplied then there is no vaporizer. The pressure regulation is demand type. The reason some engines require liquid supply is due to the volume of fuel potentially consumed. Since propane expands 270 times when not under pressure more fuel cam be supplied at the engine by supplying liquid rather than vapor. I.e. a vapor supply would require a significantly larger diameter supply hose.
Most small cid engines utilize a vapor supply.
And that's why your gen exhaust smells now vs. originally.
A shop that repairs forklifts will have someone familiar with LP fueled engines. They may not know anything about the generator itself.
I hope this will help you.

[Olefrank]

I appreciate all the help from you folks. I'll check with Cummins to see if they agree with what CW did and I'll even go to a forklift shop to see what they say about the smell. Again thanks all,
Frank

[Olefrank]

97Windsor, I haven't had a chance to use it much as it ceased to function the 2nd day I was using it. The first day it ran both roof ACs all day (10 hrs) and the 2nd day it ran 5 minutes and quit. Now it starts hard and runs, and the exhaust smells strongly, not like captan, but like a strong burnt LP smell.