My Onan 4000 which only has about 80 hours stops working. I think it is because I do not exercise it monthly. I pay around $300 to replace the caburator, but I am thinking about buying a portable generator (link below) . Questions: 1. Will 2000W generator able to run AC in a 22 ft RV (Model is winnie minnie 22r)2. Do you still have to exercise portable generators monthly? thankshttps://www.walmart.com/ip/A-iPower-SUA2000i-2000W-Digitial-Inverter-Generator/784816626?irgwc=1

Won't cut it, Cody. Your AC + converter will require approx 2000-2200 watts, steady state. Note that this genny will deliver 1600 watts steady state; not 2000.Suggest you not give up on the Onan just yet and, instead, find someone who will troubleshoot it rather than throw parts at it. The fuel pump/filter often are culprits; I actually had to replace the magneto in mine (rare problem) and it has been running fine for 4 years since.Others will have advice as well......there are a LOT of satisfied owners out there and many have a ton of expertise as well.Good luck on the fix.

Exercise makes all the difference, but a periodic tune up still costs money. We don't use ours much but ac is necessary every so often. I can refer you to KD Repair, a good shop if you're social distancing around Chicago. :-)

I would give up on the Onan as they are nothing but trouble and parts are expensive. I haven’t met an Onan that I liked yet! Buy two Honda 2000 watt generators and link them together to get 4000 watts. I did this years ago and couldn’t be happier. I do have to start by pulling but they always work. If on a tight budget then get the Champion version. You’ll only over spend and get frustrated with your Onan. Good luck!

Onan generators reliable/workhorses that tend to outlive the RV - but they do need to be exercised monthly to insure that the carburetors don't gum up. Use the forum search feature using the term Seafoam and Generator ... lots of threads on how to restore carb function using Seafoam.

Your problem is that you have a 5 year old generator that only has 80 hours on it. That's not even one full day a year. Gensets need to be run - a lot and under load. At this point it should have a few hundred hours. It's better to run a generator 24/7 than let them sit not running at all. Hard to tell what's wrong with it since it doesn't get used. But your Onan was built for your RV. It's sized properly and fits in the bin, all the wiring is set up as well as fuel lines etc. I would get it fixed rather than buy another generator. Otherwise you have a lot more work to do, like where to put the new one, wiring it up, fuel supply, ventilation and exhaust, etc etc. The root problem is lack of use and maintenance. I don't see how buying another generator will fix that problem. Do you even need a generator? Seems like you don't use the one you have. Not trying to be snarky. But fixing this one will likely be cheaper and easier than buying another one and getting that to work in your rv.On edit: I reviewed a few of your other posts an it seems like you have an RV that only gets used 1 or 2 times a year. As a result you are having issues due to lack of use. RV's - like anything else - like to be used or they start to have problems. Have you considered that you may actually be spending more money addressing things from lack of use than selling it and renting an RV for the 1 or 2 times a year? Again, not trying to be snarky, just a thought.

Replacement for Onan 4000 | Good Sam Community

pnichols
Explorer II
Apr 17, 2020
We've had the same original Onan 4000 in our motorhome since we bought the MH new in 2006.

However:
1. I run it with a load about an hour every few weeks when the MH is in storage.
2. I use Mobil 1 Extended Performance synthetic oil in it.
3. I use an E3 spark plug in it.
4. I've had it's fuel filter and air filter changed once.

I consider it essential for fully and truly self-contained, convenient drycamping ... with no concern for the weather, the sun, or the location ... because it can heat the RV, cool the RV, cook our food, refrigerate our food, blow up a flat tire, charge the coach and chassis batteries, and blow dry the wife's or dog's hair. It can do all this day or night by pushing a switch while being fueled from up to three-quarters of a 55 gallon gas tank.

We carry a small portable genny along too, just in case ... but it's rarely needed except for backup coach battery charging.

So far ... both the Onan generator and Honda EX650 portable generator have lived up to their legendary reputations.
craz_z
Explorer
Apr 17, 2020
tiffy2000 wrote:
I have a 5500 Champion for the house that has never let me down other than stupid Ethanol gas eating up stuff , carb was $35 for it.

My conclusion is the only reason to have a ONAN is its onboard and it has a remote switch.

That stupid little convenient switch is the only reason I replaced mine!

Total waste of money and i only use it for Air conditioning which in Montana is like 3 hours a day for a month. everything else on my C is powered by lithium and solar or as a backup for winter camping 1-2 weekends per year.

There are remotes on newer portable gens that can be used but then its not onboard something you gotta carry around with a hitch rack etc. gas tanks that's why they get the price they do.

With a ONAN your paying 3000$ for a switch and a place to suck gas out of your motorhome gas tank not a generator.

they are great when the magic switch cools you down in the summer and finicky as a ferrari with almost no serviceable parts when the magic switch decides not to fire it up.

I can see why some would not take one even if given for free.
tiffy2000
Explorer
Apr 17, 2020
My Onan 5500 worked great for one year then started surging, gave it the Seafoam treatment , seemed to help. Started surging again the next year , replaced the fuel pump, fuel filter worked good for that year. Next year started surging again, tried stronger mix of seafoam , didn't help and actually made it worse. Took carb bowl off, cleaned what jets I could with carb cleaner and it purred like a kitten. Left for a trip one week later , back to same old surging issue. A new carb for this model is over $300 but may have to bite the bullet and get it as I can't find a knock off carb for this model. I exercise it every month during the summer with a load on it and put fuel stabilizer in at the end of the season and run it with that in the fuel. I have a 5500 Champion for the house that has never let me down other than stupid Ethanol gas eating up stuff , carb was $35 for it.
craz_z
Explorer
Apr 17, 2020
I got very intimate with my onan before finding a deal on craigslist for a hardly used one for 1300$

I did call a ONAN service center only 1 in the state. They laughed at fixing it saying its cheaper to buy a new one then for them to look at it if you are still are interested we have a 3 month wait.

Its been awhile since I worked on the project. I did dive deep into testing and gave up. In the end I was faced with throwing an addtional 50$ in the pot for a last resort guess. Then the craigslist deal came up. took the old one to the dump.

It had 1300 hours on the house gauge and seemed like it lived its life. the engine was near perfect when i dived in to see how it worked.

new starter (not related to its death) just needed a new one.
new carb (don't know why just throwing parts at it.) I think at the time plug was wet
spark was present.
fuel was present.
no start. no run. bench tested with fuel and starting fluid. pops but no run or run at low speed and never keep running.
checked the timing key on the flywheel. (all good)
new plug x2
codes were related to no current output (duh it wont run up to speed thus no voltage current runup)
checked commutators on gen. didnt have any shorts not that it matters cause the engine wouldn't run.
compression was just fine. piston valves adjusted properly no issues.
thought about the control board but it doesnt do anything that i can see for spark or timing.

My conclusion that i gave up on was I think the magneto failed even tho it had spark. I never threw the 50$ to confirm. there was nothing left to test. I exhausted all the cheap options from bojack parts. even took what you can apart on the oem carb all clean as clean can get.
It was middle of summer and just wanted to be done messing with it and took the deal on craigslist.

The new 4000 was never used is like brand new way cleaner then the old one. was dismantled out of an rv and seldom used. i'd look on ebay and craigslist. these are dime a dozen.

Oh and P.S. NONE of the newer 4000 ky microquiets have low oil sensors. so you can cross that off the list.

air conditioning is the only use for having a generator everything else can be dealt with lithium and solar and a high quality inverter for close to the cost of a new onan.
Bea_PA
Explorer
Apr 09, 2020
Our 4000 is 8 years old, we exercise it in the summer when we are here and run stabile through it for the 4 or 5 months we are away.We have had Onans for 21 years and never had a problem with any of them.
ron_dittmer
Explorer II
Apr 06, 2020
I have lots of carbureted 4-cycle engines around the house from an 18hp lawn tractor to an 8hp roto-tiller, to a 10hp snow blower. I never have trouble with them sitting around for extended periods. I apply the same to my 4-cycle Onan which also never gives me trouble.

I just don't understand why everyone else has so much trouble with their Onan sitting without starting so frequently. It must have something to do with sitting outdoors, or they don't know how to prime it after so long of a period. Mine 4-cycle engines are all stored indoors which I am sure is influential, but still.........
Grit_dog
Navigator
Apr 05, 2020
way2roll wrote:
I would say that the folks that do not exercise their genny with no issues are just lucky and the minority. We have a whole house generator, wired to it's own sub panel etc. It starts itself up weekly and runs 2 minutes without a load and then 15 minutes with a load and then removes the load and shuts down a minute later. Why do you think the engineers designed it to do that? Personally I want to know that my things are going to work when I need them to. And that means periodically running them and proper maintenance. Storing them for months on end without doing anything is rolling the dice. That's my opinion of course and YMMV. Maintenance aside, do I want to know in the spring while prepping for a trip that mice have chewed a fuel line or wire? Or do I want to know that when I have time to fix it? Put simply if you don't properly maintain things and ensure they work the risk of failure when you need it increases exponentially.

No people who don't maintain their generators (or anything else) properly are lucky if they don't have issues.
While house system is designed to different parameters. It has large fuel reserves and is designed to operate automatically and presumably to preserve more critical systems than a portable or rv generator.
When my Honda 2k sits for more than a month or so, it needs a shot of fuel to start, everytime. Doesn't mean it's being destroyed by not being run.
Like I said earlier, frequent "exercise " is a bandaid for other measures. Proper layup eliminates or greatly reduces the "need" for other measures.

Theories presented by those who don't know much more than "gas n go" are not based off of fact, but rather the workarounds learned to prevent the bad situations.
Just like "Onans" are junk moniker. Carbs, oil sensors and fuel pumps top the list and are likely the greatest majority of issues.
But those things are only a big deal if you just "expect" something will work and not have an issue here or there.
Example, we own a wakeboard boat. Considered the top quality in that realm. The OE fuel pumps are junk for some reason, or were for about 15 years running.
People say that's junk and cost me $1500 on a $100k boat. But if you know what you're doing, it's a $100 part and a 1 hour fix with basic hand tools and you're good for another 500 hours.
ron_dittmer
Explorer II
Apr 05, 2020
Dusty R wrote:
On the prime switch. I don't it will work from the start inside, you have to do that from the start switch on the generator itself.
Interesting comment. I can prime from inside my motor home using the start switch backwards. If you are not setup for it, then most definitely pull the cover off the Onan and do it there. I would never be able to start my Onan after a long hibernation, if not for the process of extended priming.
Dusty_R
Explorer
Apr 04, 2020
ron.dittmer wrote:
Hi CodyClassB,

I did not read through all the replies, so maybe this was covered.

Before spending a penny, before taking the rig in for generator service, first try these two things.

#1 - On your Onan, set the altitude adjustment to the proper altitude. It looks like this.

#2 - Many people don't know how to properly work the "prime" feature.

At your generator control panel, be very quiet. To prime the generator, you must push in the start switch in, but in the opposing direction (it is a rocker switch). HOLD it there and listen for any kind of sound. It would be the sound of the fuel pump running. If you hear nothing, have a family member press and hold it while you are outside under your Onan.

If you don't hear any hum or buzzing sound, then your fuel pump is not working. Check fuses and such. If your hear a hum or buzz, then your fuel pump works.

On the prime switch. I don't it will work from the start inside, you have to do that from the start switch on the generator itself.
Also, Listen very closely to the fuel pump when you are holding the switch. You can hear a difference when the carb bowl gets full, the pump it gets quieter.

Then make sure your main fuel tank is at least 1/2 full.

People don't realize how long they need to hold in the prime button to get fuel from the main fuel tank to their Onan. Each rig is different pending the distance between them.

Prime, prime, prime. I advise to do as I do. Hold in the prime button for 15 seconds the first time and then try to start the Onan. If nothing happens, hold the prime button in for 10 seconds thereafter and repeat until it starts.

I never ever run my generator during the off season. I put the rig away in the fall and start everything up in the spring time. A few years, our rig will sit an extra year, and everything always starts right up. I do maintain the batteries during off season. This has been my practice with our rig for 13 years. We do store our rig indoors in a climate controlled environment which I am sure makes some difference. But I never understood all the talk about monthly start-ups and such, though some necessity if the rig is stored in the worst of conditions.
way2roll
Navigator II
Apr 04, 2020
I would say that the folks that do not exercise their genny with no issues are just lucky and the minority. We have a whole house generator, wired to it's own sub panel etc. It starts itself up weekly and runs 2 minutes without a load and then 15 minutes with a load and then removes the load and shuts down a minute later. Why do you think the engineers designed it to do that? Personally I want to know that my things are going to work when I need them to. And that means periodically running them and proper maintenance. Storing them for months on end without doing anything is rolling the dice. That's my opinion of course and YMMV. Maintenance aside, do I want to know in the spring while prepping for a trip that mice have chewed a fuel line or wire? Or do I want to know that when I have time to fix it? Put simply if you don't properly maintain things and ensure they work the risk of failure when you need it increases exponentially.

Forum Discussion

Replacement for Onan 4000

About Motorhome Group

Related Content

Onan microlite 4000

4000 onan

Onan Generator 4000

Onan 4000 hose replacement

New Onan 4000 wont start