Is this a Generator or A/C Problem

On Saturday, my wife and I were driving north on I-15 south of Barstow. Exit 165 (Wild Wash Rd) Had an inside dual go down. (no damage to RV) We were going to Las Vegas on business.
We got off the HWY, I Called Coach-Net, another post in it's self, )at 1645hrs.

Being as it was over 100 degrees and we had our Throw Away Dog (we rescued him from the Animal Shelter) I started the Onan Microlite 4000, it seemed to run like it was struggling,
When I first went to start the Generator it did not catch. Pushed the re-start button it started. When it first started, it took a couple of moments for it to come up to speed. The generator seemed to surge a couple of times. It was very hot outside temp. I opened the generator compartment door so it would have better outside air circulation. I ran the generator for about 5min before we turned on the Air Conditioner. I did check the oil before we left the storage yard. We were not low on fuel had over 3/4 of a 55gal. tank. According to the monitor inside the RV it was putting out 118v and fluctuating between 120v held mostly @118v.
I have only run the A/C on the Generator maybe 3 times. There are only 215hrs. on the Generator.
(I opened the side access door to the Generator compartment for better ventilation) then when we started the Air Conditioning (1 unit Coleman Mach 3) it would run for a minute or two and then shut off. (The A/C) That was using the Auto set on thermostat or turning it on manually. The generator was putting out 118v. Rather than burn out the A/C I shut it down, and opened all the windows. Also shut down the generator.

Last year I had some what the same problem took it to an Authorized Onan Service Center
The Onan Authorized dealer that repaired the unit last year, changed the Carburetor & Fuel Filter. Put fresh 30w Oil in it. New Air Filter also.

We get the tire changed drive to the KOA campground in Yermo Barstow/Calico. We got to campground at 2045hrs.(people bad mouth KOA, but you think about it and their prices are about what the going rate is today, and they do not have a Bovine Excrement age limit rule) We called a campground in Las Vegas and were told because our Class-C RV is a 2005 they would allow us it stay there but next year we couldn't use their campground. :h :S

We get set up in our camp site, I check power pedestal (putting out 125v) Plug RV in to AC Power, Air Conditioner runs great, :face palm:

Being as we had no spare and could not find one we turned around and came home. (Also do not trust the slugs that work at the tire shop to put 80psi in the tires, always check them yourself) I asked the clown to put 80psi in all the tires, every tire on the RV was at 65psi. I really should have watched him while he was doing it I really think he was just trying to placate me. :M When I used to drive trucks cross country I used to check air pressure in all of my tires before I would start out, and every three hours I would stop and walk around and check the tires and other things on the rig. I guess I better start doing that again before I even l think about leaving the storage lot.

I think there might be something wrong with the Onan, we had this problem once before and had it fixed last year. I have the GS CSP I think it's time to take the unit in to get it worked on again.
I can say this there was no damage to the RV (maybe a little to my pride) No one was hurt or injuried, we got home safely. We didn't need to go to Las Vegas anyway.

Mandalay_Parr
Explorer
Oct 07, 2014
After repair you probably need to run it more. I run mine monthly with a high load for 30 minutes. Keeps the fuel fresh and in good working order.

I have an 05 with over 1200 hours on the gen. Never any problem.
midnightsadie
Explorer II
Oct 07, 2014
I would put some sea foam in the fuel, sounds more like clogged carb than anything, put sea foam in the fuel line run genny put a load on like turn all the lights on, I too run mine 1hr per month.
ksg5000
Explorer
Oct 07, 2014
Sounds like typical Onan problem caused by not using it on a regular basis - carb gets gummed up. Lots of posts on that subject - suggest you use the forum search feature using the terms Onan and Seafoam. In the future I would suggest you run your generator once a month for about two hours (hook up an electric heater to put a load on it - or maybe air conditioner if it's too hot).
wa8yxm
Explorer III
Oct 07, 2014
Several thoughts come to mind,, First, from your use of the word Carburetor I assume yours is a Gasoline rig.. This is important to me because if it was a Diesel I'd not be replying.

ON a Gasoline Onan Generator there are two devices that might cause this kind of "Surging" you mention.

One is the altitude adjustment on the carbureator.. You set it manually, Your GPS will give you the altitude you are parked at just set the thing to the same setting, This adjusts the air/fuel mix a bit as the air on top of mount Everest is a tad lower in oxygen that say the air at the bottom of Death Valley (Ok, it does not even have to be that much difference) if its set too high you get stuttering and too low you get surging if I recall correctly (And please do not make book on my memory here I could have it backwards)

The second is the automatic choke.. This reduces air entry so as to increase the air fuel ratio, it should be fully closed (or close to it) when you press teh START button, then once the unit starts rapidly open, this can take a couple of minutes depending on many things. It too will cause some rough running till it fully opens.. 100% normal for the generator.

I wish mine opened faster .
naturist
Nomad
Oct 07, 2014
It does indeed sound like gummed up carb from lack of use. And I agree that the wise generator owner runs it once a month for a half hour or so, just to keep the fuel in the carb fresh and the oil from draining completely out of everything, so cylinder walls don't rust, etc.

Every time we have a storm around here, with folks out of power for a day or three, I run into SOMEBODY who bought a generator last time around, ran it then to make sure it worked, hasn't touched it since (maybe a year or more ago) and now is distressed to discover they can't get it started.

I also agree, you can't trust the guys at the tire shop to put in the right amount of air -- regardless of the tire or the application. Face it, they do NOT hire rocket scientists to change tires, they hire whoever they can get for minimum wage. Those guys are not paid to think, they are paid to pull tires off rims, put new ones on, and blow 'em up, and 32 lbs for cars, 65 lbs for trucks works to get 'em out the door for the next one.

I've vehicles that are supposed to have varied tire pressures (NONE of which is 32, btw), and every time one of them gets new shoes, I drive them home, let them cool, check the pressure, and guess what? 32 psi. every time.
DougE
Explorer
Oct 07, 2014
When the oil change guys check the tires they never put the valve caps on tight either. I realized this several decades ago when I finally noticed that valve cap losses corresponded with oil changes. One ounce/gallon of Seafoam takes care of gum prevention.
PatrickA51
Explorer
Oct 07, 2014
midnightsadie wrote:
I would put some sea foam in the fuel, sounds more like clogged carb than anything, put sea foam in the fuel line run genny put a load on like turn all the lights on, I too run mine 1hr per month.

I use Sea-Foam or Sta-Bil Fuel Treatment, in the tank when I park the rig, The generator runs good after it has run for a couple of minutes.
PatrickA51
Explorer
Oct 08, 2014
I went over to the RV this afternoon. Generator starts, seems to surge. I again checked the oil , not all the way to full but in the safe zone. I checked the breaker switch,(not tripped)I also checked the altitude adjustment on the carburetor..it was set for 5000ft. I started the generator,(before I started it I sprayed Sea Foam in the carb. I also put a can of Sea Foam in the gas tank. it ran fine, 121v,surged a little bit. I turned the Air Conditioner on it ran for a couple of minutes and shut down for a minute or two, and then started and stopped.I went out and checked the breaker switch, this time it was tripped. Generator still ran no out put voltage. The breaker switch was tripped. I set it started the generator, it runs no out put voltage,now.
j-d
Explorer II
Oct 08, 2014
I had a Battle Royal with our little ONAN 4KY Spec K genset 4KW till I replaced the carburetor. People I bought the coach from had "just" (within a couple months) had one installed and it wouldn't run from non-use, just that quick. They have TINY fuel passages that gum up easily and are convoluted enough to make them about impossible to clean.
You can try disconnecting the fuel line to the carburetor (the one from the fuel pump) and filling with Sea Foam, Berryman, whatever your favorite cleaner is, and seeing if it'll start and run a few minutes. Let it stand, and repeat, repeat. Another way is to make up a gallon can with a heavy concentration of cleaner and put the pump suction line into it so the genny runs on a heavy concentration of cleaner. BE CAREFUL OF FIRE!!! The RV's feed line will have to be carefully plugged. You need to keep the gallon gas supply upright and away from the hot genny and its exhaust. If you get it to stabilize, put a load like your coach A/C on it and let it RUN! For Hours! May just clean itself up.

Part I don't understand is loss of output. With all the trouble I had with ours, it never lost its ability to put out 120VAC if the engine would run.

I now put StaBil in every fillup whether traveling or not. I also run the genny monthly. It was such a pain, took so long to fix (really till I gave up and got a carb) that I don't ever want to go through it again.

Post your full Model and Spec here, and somebody may be able to link you to a manual with troubleshooting.
PatrickA51
Explorer
Oct 08, 2014
j-d wrote:
I had a Battle Royal with our little ONAN 4KY Spec K genset 4KW till I replaced the carburetor. People I bought the coach from had "just" (within a couple months) had one installed and it wouldn't run from non-use, just that quick. They have TINY fuel passages that gum up easily and are convoluted enough to make them about impossible to clean.
You can try disconnecting the fuel line to the carburetor (the one from the fuel pump) and filling with Sea Foam, Berryman, whatever your favorite cleaner is, and seeing if it'll start and run a few minutes. Let it stand, and repeat, repeat. Another way is to make up a gallon can with a heavy concentration of cleaner and put the pump suction line into it so the genny runs on a heavy concentration of cleaner. BE CAREFUL OF FIRE!!! The RV's feed line will have to be carefully plugged. You need to keep the gallon gas supply upright and away from the hot genny and its exhaust. If you get it to stabilize, put a load like your coach A/C on it and let it RUN! For Hours! May just clean itself up.

Part I don't understand is loss of output. With all the trouble I had with ours, it never lost its ability to put out 120VAC if the engine would run.

I now put StaBil in every fillup whether traveling or not. I also run the genny monthly. It was such a pain, took so long to fix (really till I gave up and got a carb) that I don't ever want to go through it again.

Post your full Model and Spec here, and somebody may be able to link you to a manual with troubleshooting.

I have the same unit ONAN 4KY Spec K genset 4KW.
As you can see from my post above I had the generator worked on about 16 months ago. I still have the old parts. I would not let the service shop keep, it. (I was told by a friend that took his RV out there to them and he told me how the man that worked on his made a comment about them rebuilding the carbs, and then selling them as new, I don't know how true what he said is but, I have no reason to disbelieve him. I have known this man for many years)