Onan generator carb?

[OutCole'd]

So on my 2017 RV, onan generator 4000, generator wont start. Fuel is getting there, but nothing. I had a few minor warranty issues to get handled, so I brought it to the dealer, had them look at the genny and they are telling me the carb is gummed up, not covered by warranty and about $400 to fix.

I mostly use the generator in the Winter months when out in the desert, but the Summer months not so much, when we use the RV then, it’s usually full hook up spots. I still run the genny every month, but only for 10 minutes or so, and with no load. I’m now being told by the dealer I’m supposed to run the genny at least once a month for 1-1-1/2 hours with a load (news to me).

Any suggestions or just find the carb online and put it on myself, seems like they are about $250 or so.

 

[4Waters]

Replace it and start and run the generator once a month for about 20min and you won't have any more problems.


Edit: Finished reading your post, but I have never had an issue with 20min maybe 30min of running a month.

 

[rrrr]

Read your owner's manual. I doubt it gonna say run the genset under load once a month. If it doesn't, you have an argument for warranty repair. Besides, they can't say that's the issue unless the car has been removed and inspected, which probably didn't happen.

I think there's a fuel solenoid needle valve on those units, and they can get sticky, fail to open, and no joy. If you're handy at all or have a friend that is, they aren't difficult to disassemble and fix.

 

[guest hs]

I had a onan 5500 that I took the carb off twice a year and cleaned it out. I now have a 4000 onan I make sure I keep stabilizer in it and there is a drain screw on the float bowl I open up after every time I use it.

 

[OutCole'd]

Read your owner's manual. I doubt it gonna say run the genset under load once a month.

I think there's a fuel solenoid needle valve on those units, and they can get sticky, fail to open, and no joy. If you're handy at all or have a friend that is, they aren't difficult to disassemble and fix.

I tore the carb all the way down today, cleaned it best I could using carb clean and an air compressor, still nothing. They don’t even sell carb kits for the POS’s, they are not meant to be rebuilt.

 

[Uncle Dave]

The 4000 carbs are nearly impossible to rebuild and you'll find a garbage can full of them every genset place.

You need to drain it every time you put it away- its easy and you dont even need tools. (mayeb a screwdriver) Same with altitude adjustment on that genset- its a knob.


Once it starts surging seafoam may bring it back - but a new one is the quickest route to happiness.

 

[OutCole'd]

I had a onan 5500 that I took the carb off twice a year and cleaned it out. I now have a 4000 onan I make sure I keep stabilizer in it and there is a drain screw on the float bowl I open up after every time I use it.

Draining the carb, that’s a great idea! Thanks

 

[OutCole'd]

I’m wondering if I will have any luck getting Onan to warranty a new carb?

 

[rrrr]

Does the carb have a power wire going to the body? If it does there's a needle valve. The needle has to move freely in the valve body.

 

[JDKRXW]

X2 on draning the carb when you're not going to use it foe a month or 2.

 

[Uncle Dave]

I may even have one my last toy hauler had a 4K in it - Ill go look if I do you can have it.

By and large, I hated that genset and always brought a Yamaha in the back of the truck or 2 hondas with me.

UD

 

[OutCole'd]

I may even have one my last toy hauler had a 4K in it - Ill go look if I do you can have it.

By and large, I hated that genset and always brought a Yamaha in the back of the truck or 2 hondas with me.

UD

I use my little honda 90% of the time, and only run the big genny for the higher load stuff.

 

[OutCole'd]

Does the carb have a power wire going to the body? If it does there's a needle valve. The needle has to move freely in the valve body.

Yes it does, I’ll look at that next.

 

[Uncle Dave]

I use my little honda 90% of the time, and only run the big genny for the higher load stuff.

One you have to start the AC its ok because of the AC noise masks the genset - at least inside.

It drank like 1/3 gallon an hour just idling charging phones and laptops and stuff- 1 speed 3600RPM roaring away with no load.

No problems from it - as long as you drain it each time, just lots of noise and consumption.

Just looked- I do not have the carb anymore - I may have given it to the guy I sold the toyhauler to.

UD

 

[OutCole'd]

One you have to start the AC its ok because of the AC noise masks the genset - at least inside.

It drank like 1/3 gallon an hour just idling charging phones and laptops and stuff- 1 speed 3600RPM roaring away with no load.

No problems from it - as long as you drain it each time, just lots of noise and consumption.

Just looked- I do not have the carb anymore - I may have given it to the guy I sold the toyhauler to.

UD

Ok, thanks for looking!

 

[warlock250]

I have cleaned a lot of them little onan 4k carbs in the past. Sometimes I would take a small strand of wire to clean the passages after soaking the carb in a acetone and transmission fluid mix overnight and ream the holes good as they are so tiny it doesn't take much to lose diameter and reduce flow. Sometimes it has to be done twice. And clean the electric choke piece on bottom of the bowl really well also.
The onan Owners guide clear states that the generator needs to be run 30 minutes a month. They want fuel flow and to also keep rotor plates from sticking together. Lots of parts inside that need to stay freed up. Best running generator is one that has lots of hours on it.

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[cakemoto]

I have a 4000 with 200 hours. Thing starts runs bitchen for about 40 min then it starts surging. I have done the seafoam and fuel filer with no luck.it never dies out just cuts in and out

 

[Taboma]

Stabilizer should help as well. But wait there's more

Seriously, everything you read keeps blaming ethanol in the gas --- well OK, but how come my pre-CARB regulated Honda Generator, with no fuel shut-off, will fire right up and run on year old ethanol gas, no problem at all ?
Same goes for my older B&S powered lawn mower and my old beater grove mower, gas so old it's next evolutionary stage will be varnish, push the primer, fires up and mows with plenty of gusto. Ditto my older Echo weed whacker, it will start fine and run on anything.

The ONLY problems I've encountered is with any newer gas gennies or yard implements.
For giggles I was checking the specs and info for a new lawn mower, only cuz mine developed a nasty "THUNK", was thinking it's about to toss a rod --- Shit !! So I'm reading all the reviews on the new mowers, both B&S and Honda --- complaint after complaint of them not starting after sitting a couple of months, even with stabilizer. Warranty repairs refused because the fine print (One that I did read) stated --- Drain the gas (No shut-off on B&S), then run it till it dies. Then start it and run it for several minutes once a month --- Hold on, you just had me drain the gas, now re-fill it, start it, run it, then drain the gas AGAIN and run it till it dies. Oh Good Lord you must be joking !!
The complete irony is this -- B&S and Honda now come with a new hi-tech (Yeah like late 1940's tech) automatic choke, so no manual choke or primer --- claim is "So simple anybody can start it and mow" (Pay attention millennials --- even you dumb-asses can mow a lawn now !!) --- but wait, who's going to be draining and refilling the tank once a month ??
The same clown who can't use a manual choke or push a primer button 4 or 5 times, but your going to trust him or her handling raw gasoline ??
Anyway, my mower clunk and thunk was due to a new blade I install and I discovered the shoulder on the shaft wasn't allowing the blade to suck down tight on the mount --- whew
FYI, I did check and there is a Non-Carb mower that can be ordered and shipped to HD Lake Havasu, but it still has the high-tech automatic choke Otherwise, all their gas engines are CARB.

 

[guest hs]

I’m wondering if I will have any luck getting Onan to warranty a new carb?

I would be very very surprised if they warrantied a carb due to bad fuel in it. Don’t hold your breath just clean it move and learn from your mistakes

 

[pronstar]

I had a brand-new Yamaha 2800 gennie, second trip out, wouldn’t start.

Gummed up carb, not covered under warranty because it’s considered bad gas.

Ran stabil in it, and ran the carb dry after each use - just turn the fuel petcock off and let it run until it dies.
Never an issue afterward.

Had a similar issue with the genset in my toy hauler. New carb and stabil prevented it.

I run stabil in everything now, just add it to my gas can.

Ethanol is terrible for new carbs.




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[TPC]

Ya gotta run them.
Carry a spray can of carb cleaner and removing the carb is real easy.
A few straightforward You Tubes on it.

The straw on the carb cleaner can help get into the nooks and flow ways etc.
most the time that’ll do it.
We always have several the first few trips of The Glamis season and a simple cleaning does it.

 

[aka619er]

I added an inline valve to the carburetor of my Onan 4k and shut it off every time I'm going to store it. Then I let the gen run until dies the same as you would with atvs/motorcycles. Never had an issue.

 

[Uncle Dave]

Wish my honda 2K's had a fuel cutoff like the little yamahas do - you have to go behind eth cover with a screwdriver and drain them manually.

You can blow off the stabil if you run it dry then fire it back up on 2-3 gallon of race gas, but you have to purge the lines and carb. It doesn't work to just make a mix.

 

[tkrrox]

Get one of the ultrasonic cleaners and drop the bowl in.


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[TITTIES AND BEER]

Replace it and start and run the generator once a month for about 20min and you won't have any more problems.


Edit: Finished reading your post, but I have never had an issue with 20min maybe 30min of running a month.

I just went through this 600$ to replace carb then I sold it

 

[4Waters]

Stabilizer should help as well. But wait there's more

Seriously, everything you read keeps blaming ethanol in the gas --- well OK, but how come my pre-CARB regulated Honda Generator, with no fuel shut-off, will fire right up and run on year old ethanol gas, no problem at all ?
Same goes for my older B&S powered lawn mower and my old beater grove mower, gas so old it's next evolutionary stage will be varnish, push the primer, fires up and mows with plenty of gusto. Ditto my older Echo weed whacker, it will start fine and run on anything.

The ONLY problems I've encountered is with any newer gas gennies or yard implements.
For giggles I was checking the specs and info for a new lawn mower, only cuz mine developed a nasty "THUNK", was thinking it's about to toss a rod --- Shit !! So I'm reading all the reviews on the new mowers, both B&S and Honda --- complaint after complaint of them not starting after sitting a couple of months, even with stabilizer. Warranty repairs refused because the fine print (One that I did read) stated --- Drain the gas (No shut-off on B&S), then run it till it dies. Then start it and run it for several minutes once a month --- Hold on, you just had me drain the gas, now re-fill it, start it, run it, then drain the gas AGAIN and run it till it dies. Oh Good Lord you must be joking !!
The complete irony is this -- B&S and Honda now come with a new hi-tech (Yeah like late 1940's tech) automatic choke, so no manual choke or primer --- claim is "So simple anybody can start it and mow" (Pay attention millennials --- even you dumb-asses can mow a lawn now !!) --- but wait, who's going to be draining and refilling the tank once a month ??
The same clown who can't use a manual choke or push a primer button 4 or 5 times, but your going to trust him or her handling raw gasoline ??
Anyway, my mower clunk and thunk was due to a new blade I install and I discovered the shoulder on the shaft wasn't allowing the blade to suck down tight on the mount --- whew
FYI, I did check and there is a Non-Carb mower that can be ordered and shipped to HD Lake Havasu, but it still has the high-tech automatic choke Otherwise, all their gas engines are CARB.

My carb takes a shit about every 2yrs on my Briggs and Stratton lawnmower and 4 stroke weedeater, 3 years ago I put a new carb on the lawnmower and maybe about 2.5 years ago on the weedeater and switched to true fuel and have no problems at all since.

 

[TITTIES AND BEER]

My carb takes a shit about every 2yrs on my Briggs and Stratton lawnmower and 4 stroke weedeater, 3 years ago I put a new carb on the lawnmower and maybe about 2.5 years ago on the weedeater and switched to true fuel and have no problems at all since.

Onan carbs are POS ( sells man told me that ) everything on our ranch before it put away we shut off the fuel and let it run out even if we are using it the next day

 

[Taboma]

My carb takes a shit about every 2yrs on my Briggs and Stratton lawnmower and 4 stroke weedeater, 3 years ago I put a new carb on the lawnmower and maybe about 2.5 years ago on the weedeater and switched to true fuel and have no problems at all since.

Both my B&S powered mowers are roughly 15 years old and the carbs have never been touched. The 2 stroke Echo weed whacker is 10, four primes and it starts first pull with last seasons gas in the tank. I'll keep that Trufuel info handy in case I have to purchase any new yard implements. For now, I'll keep burning stabilized varnish, lol
But I know you're not alone, every review no matter the equipment agrees with your experience.

 

[Taboma]

Onan carbs are POS ( sells man told me that ) everything on our ranch before it put away we shut off the fuel and let it run out even if we are using it the next day

I did notice the newer Honda power mowers have a fuel shut-off, didn't them on the Briggs and Strattons, but if I get a new anything, I'll install one.

 

[warlock250]

I usually have 5 to 10 gallons of AV fuel.at home for small engine applications. It never goes bad and the little engine carbs never ever gum up on it. Cause it wont varnish up. Lol

Wish my honda 2K's had a fuel cutoff like the little yamahas do - you have to go behind eth cover with a screwdriver and drain them manually.

You can blow off the stabil if you run it dry then fire it back up on 2-3 gallon of race gas, but you have to purge the lines and carb. It doesn't work to just make a mix.

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[4Waters]

Both my B&S powered mowers are roughly 15 years old and the carbs have never been touched. The 2 stroke Echo weed whacker is 10, four primes and it starts first pull with last seasons gas in the tank. I'll keep that Trufuel info handy in case I have to purchase any new yard implements. For now, I'll keep burning stabilized varnish, lol
But I know you're not alone, every review no matter the equipment agrees with your experience.

My mower was my moms that she bought right after the Northridge earthquake as the old one was crushed in the garage when everything that fell on it. She gave it to me about 15yrs ago and I had already done a couple of carbs on it by then. Trufuel smells like gasoline from the 70s, it smells great.

 

[wsuwrhr]

My Onan will happily runs for days on end and then die like you hit the kill switch, it will refire and run fine for another three days, or 3 min, just depends. Been doing that for years. If I take the coach somewhere to have someone look at it, it will run for days on end, I pick the coach up and the genset dies as soon as I round the corner from the shop. Bring it right back and it will run for another three days on end.

Been that way for years, I just gave up.

 

[Taboma]

My Onan will happily runs for days on end and then die like you hit the kill switch, it will refire and run fine for another three days, or 3 min, just depends. Been doing that for years. If I take the coach somewhere to have someone look at it, it will run for days on end, I pick the coach up and the genset dies as soon as I round the corner from the shop. Bring it right back and it will run for another three days on end.

Been that way for years, I just gave up.

By give up, you mean you beat it to death with a BFH Damn, that's a horror story about an engine possessed by some evil entity

 

[wallnutz]

My Onan will happily runs for days on end and then die like you hit the kill switch, it will refire and run fine for another three days, or 3 min, just depends. Been doing that for years. If I take the coach somewhere to have someone look at it, it will run for days on end, I pick the coach up and the genset dies as soon as I round the corner from the shop. Bring it right back and it will run for another three days on end.

Been that way for years, I just gave up.

Mine does the same damn thing. They tell me it’s an over voltage thing, but can’t fix it if they don’t see it happen.

I have two carbs for my Onan 5500.if one gets gummed up I put the other one on and take the gummed up one apart and soak it in carb cleaner for a couple weeks. Blow it all out and put it back together so I have a good one to put back on.

 

[wsuwrhr]

Short of putting a new genie in it, I have just played it's game.

By give up, you mean you beat it to death with a BFH Damn, that's a horror story about an engine possessed by some evil entity

 

[USMC2010]

I run out 4000 for about an hour once a month. This year I went from Memorial Day until about a month ago without, it took about an hour to get it running but I escaped the failed carb deal.

 

[HavaToon]

Sea Foam works miracles


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[OutCole'd]

View attachment 681256 Sea Foam works miracles


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Yep, tried that in a seperate gas can mixed heavily, still could not get it to run long enough to clean anything out. Looks like maintenance is key here folks, don’t let it get that bad.

 

[Tooned Up]

pm your number.... I will walk you through what you need to do and can pretty much guarantee you it will run again without buying a new carb.

 

[rrrr]

This video shows exactly what I was saying about the solenoid. The carb is a little different than the one on the Kawasaki engine powering my John Deere lawn tractor, but it's pretty much the same fix I was able to make. The Kaw doesn't have the leaning (altitude) compensation.

The solenoid must move freely in the valve body to allow gas into the bowl. The surging is fuel starvation because the leaning jet orfice becomes clogged with debris. This should be an easy fix.

 

[DRYHEAT]

I usually have 5 to 10 gallons of AV fuel.at home for small engine applications. It never goes bad and the little engine carbs never ever gum up on it. Cause it wont varnish up. Lol

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I have a friend that runs race gas and all his little small engines and he swears by it.

 

[OutCole'd]

This video shows exactly what I was saying about the solenoid. The carb is a little different than the one on the Kawasaki engine powering my John Deere lawn tractor, but it's pretty much the same fix I was able to make. The Kaw doesn't have the leaning (altitude) compensation.

The solenoid must move freely in the valve body to allow gas into the bowl. The surging is fuel starvation because the leaning jet orfice becomes clogged with debris. This should be an easy fix.

Great video, thanks!

 

[rrrr]

Short of putting a new genie in it, I have just played it's game.

Have you ever heard of this solution?

.

 

[wallnutz]

Have you ever heard of this solution?

.

That’s a known trick for the 4000, it doesn’t have an effect on the 5500’s though. Good tip though.

 

[TITTIES AND BEER]

N

View attachment 681256 Sea Foam works miracles


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Nope don’t work , I pulled my carb off took it to the bench 3 times tore it down as far as I could go , cleaned it , blew it out , pos still didn’t work

 

[wsuwrhr]

I believe mine is the 5500 as well, dual breaker 50 amp model.

That’s a known trick for the 4000, it doesn’t have an effect on the 5500’s though. Good tip though.

 

[HavaToon]

Yep, tried that in a seperate gas can mixed heavily, still could not get it to run long enough to clean anything out. Looks like maintenance is key here folks, don’t let it get that bad.

Use the spray version at the carb until you can get it to run then let it run a while with the in tank version.


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[HavaToon]

N

Nope don’t work , I pulled my carb off took it to the bench 3 times tore it down as far as I could go , cleaned it , blew it out , pos still didn’t work

Sea foam isn’t a bench cleaner. There’s two version the spray and liquid. Liquid gets mixed with gas and will work if your carb isn’t to bad. The spray must be used with the carb on the generator while you are trying to start it/run it. When you spray the motor will cough and sputter like it wants to die, stop spraying and let it recover, once it recovers repeat the process until you are satisfied how the motor is running.

I run 91 octane with one bottle of Lucas octane boost and stabil in my 30 gal fuel tank on the Toy Hauler. It makes it run like a top and actually with the better fuel I noticed it runs quieter as well.


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[grumpy88]

In 10 years I have bought 4 carbs and 2 fuel pumps for my 4k . Now I try to run it every week while I'm mowing the grass . I figure I will piss off the neighbors in one shot .

 

[sfury]

I added an inline valve to the carburetor of my Onan 4k and shut it off every time I'm going to store it. Then I let the gen run until dies the same as you would with atvs/motorcycles. Never had an issue.
View attachment 681207

This ^


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