onan 4000 w generator not working properly, any ideas?

Bfloxword

Member
Joined
May 1, 2021
Posts
22
Location
north carolina
My 2003 unit was bought used about 4 years ago, and, for the most part, we've been able to figure out how to use almost everything. For whatever reasons, we never had much need for the generator and neglected it until recently. I began renting the RV out through O------, so I decided to find out how well the generator was working.... oops, it wasn't, Though I had started it once in awhile to show somehow how it was started, I never ran it for more than a minute or two. Suddenly, it wouldn't start. After consultation, I decided the problem was likely a gummed up carburetor...so, I bought a new one (not expensive at all) and managed to install it myself. It immediately started and ran well. Horray! Then a custome decided they needed the generator for a chilly night in the Smokies. Oh, s----! She reported it ran for a few minutes, maybe 5 or 6, then suddenly died. O--"s road service folks suggested the oil level switch was causing the shutdown, maybe, as it is a known weak point, if the unit isn't level and the oil is not right up to the top. That wasn't something she could deal with, where she was, so she altered her plans, put the kids into her sister's house, and ran the RV engine (V10) occasionally to warm the interior for that night. So, on return, I looked it over, started it, and it ran perfectly for about 7 minutes before simply stopping.

A '41' code showed up, No power output. Well, no, there wouldn't be after the engine stopped, would there? I can't tell if the system is sophisticated enough to preserve the actual cause of the shutdown. An on line mechanic basically referred me to the onan manual for that unit and charged me $37. I called the outfit I bought it from 4 years back and they, too, didn't have anything new to add. "Bring it in, we'll probably be able to diagnose the problem in two hours of investigation ($200), but we have got 50 other units lined up in the. yard we need to recondition for sale." I understand.

So, folks, Have Anyone Here Had a Similar or the Same Problem???? What to do to fix it?

I can't say if the problem existed always, because I never really ran it long enough to know.

In the same vein, has anyone abandoned the expensive to fix generator and tried a portable inverter unit? How did that work out?
 
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My 2003 unit was bought used about 4 years ago, and, for the most part, we've been able to figure out how to use almost everything. For whatever reasons, we never had much need for the generator and neglected it until recently. I began renting the RV out through O------, so I decided to find out how well the generator was working.... oops, it wasn't, Though I had started it once in awhile to show somehow how it was started, I never ran it for more than a minute or two. Suddenly, it wouldn't start. After consultation, I decided the problem was likely a gummed up carburetor...so, I bought a new one (not expensive at all) and managed to install it myself. It immediately started and ran well. Horray! Then a custome decided they needed the generator for a chilly night in the Smokies. Oh, s----! She reported it ran for a few minutes, maybe 5 or 6, then suddenly died. O--"s road service folks suggested the oil level switch was causing the shutdown, maybe, as it is a known weak point, if the unit isn't level and the oil is not right up to the top. That wasn't something she could deal with, where she was, so she altered her plans, put the kids into her sister's house, and ran the RV engine (V10) occasionally to warm the interior for that night. So, on return, I looked it over, started it, and it ran perfectly for about 7 minutes before simply stopping.

A '41' code showed up, No power output. Well, no, there wouldn't be after the engine stopped, would there? I can't tell if the system is sophisticated enough to preserve the actual cause of the shutdown. An on line mechanic basically referred me to the onan manual for that unit and charged me $37. I called the outfit I bought it from 4 years back and they, too, didn't have anything new to add. "Bring it in, we'll probably be able to diagnose the problem in two hours of investigation ($200), but we have got 50 other units lined up in the. yard we need to recondition for sale." I understand.

So, folks, Have Anyone Here Had a Similar or the Same Problem???? What to do to fix it?

I can't say if the problem existed always, because I never really ran it long enough to know.

In the same vein, has anyone abandoned the expensive to fix generator and tried a portable inverter unit? How did that work out?
 
a bit of added information. I checked the 120 v power in the RV while connected to 'shore power' and got 114v. Disconnected shore power, started generator.... 120 and 121 volts immediately appeared, and remained steady for 7 minutes until the generator shut itself down. code 41 again appeared, but I think that could just be because the unit quit and thus quit sending power.

I am increasingly focusing on the carburetor. Perhaps I connected the linkages improperly as I changed the carb. Or, Heaven Forfend! the carburetor is defective in some way? In other words, does it cause the shutdown by engaging the choke when the temperature reaches 'operating temperature'?
 

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Maybe I'll take a video of the linkage from about 4 minutes on to shutdown. See if something changes, then it shuts down, or... it shuts down and then something changes?

Any ideas? My next booking goes out tomorrow afternoon, and is bringing her own generator, hoping her paragliding weekend at Pilot Knob is not ruined.
 
I know on the larger Onan this type of problem was due to oil level. Shut off can happen because of too low of oil, but I remember it was because of too full of oil. Do a search on YouTube.

Does it run good when it does run?

Is the fuel new?

Shut down also happens when the fuel tank gets low. The standard is 1/4 tank, but it is more like 3/8 on mine. Test with the tank full.

My final thought for now is a valve adjustment. A regular maintenance item that is often overlooked. Once the engine warms, characteristics may change enough for shutdown

Good luck!
 
thanks for the insights. not likely to be a fuel problem. oil level is at the top. Too high? First I've heard it could be. I added, though, when low level was suggested, so, it was lower earlier. Runs well while it runs. Still wondering if when it gets up to temp, the carb linkage somehow causes a shutdown. The valve settings... Presume if I remove the obvious cover, I can adjust the slap to, maybe, .002-.003 inches? Not too huffed by this possibility, I'd think it would begin running poorly before getting so bad as to shut down. Nope, it is running nicely, then suddenly quits.
 
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If the main tank of gas is at the 1/4 full mark the Generator will not work or may starve for gas. This is a common problem. It is by design, so you don't run out of gas to get your RV to the next station. Check the fuel level and add gas as that may be the only problem.
 
My 2003 unit was bought used about 4 years ago, and, for the most part, we've been able to figure out how to use almost everything. For whatever reasons, we never had much need for the generator and neglected it until recently. I began renting the RV out through O------, so I decided to find out how well the generator was working.... oops, it wasn't, Though I had started it once in awhile to show somehow how it was started, I never ran it for more than a minute or two. Suddenly, it wouldn't start. After consultation, I decided the problem was likely a gummed up carburetor...so, I bought a new one (not expensive at all) and managed to install it myself. It immediately started and ran well. Horray! Then a custome decided they needed the generator for a chilly night in the Smokies. Oh, s----! She reported it ran for a few minutes, maybe 5 or 6, then suddenly died. O--"s road service folks suggested the oil level switch was causing the shutdown, maybe, as it is a known weak point, if the unit isn't level and the oil is not right up to the top. That wasn't something she could deal with, where she was, so she altered her plans, put the kids into her sister's house, and ran the RV engine (V10) occasionally to warm the interior for that night. So, on return, I looked it over, started it, and it ran perfectly for about 7 minutes before simply stopping.

A '41' code showed up, No power output. Well, no, there wouldn't be after the engine stopped, would there? I can't tell if the system is sophisticated enough to preserve the actual cause of the shutdown. An on line mechanic basically referred me to the onan manual for that unit and charged me $37. I called the outfit I bought it from 4 years back and they, too, didn't have anything new to add. "Bring it in, we'll probably be able to diagnose the problem in two hours of investigation ($200), but we have got 50 other units lined up in the. yard we need to recondition for sale." I understand.

So, folks, Have Anyone Here Had a Similar or the Same Problem???? What to do to fix it?

I can't say if the problem existed always, because I never really ran it long enough to know.

In the same vein, has anyone abandoned the expensive to fix generator and tried a portable inverter unit? How did that work out?
First, main tank level I never go below 1/2 in case I break down and need to wait w/ heat/ air/ GEN; 2) running 5-7-minutes. especially if surging before dying is typical of a bad/ failing/ intermittent fuel pump. Likely old carb was good. 3) Brand/ Model # on GEN would help? 4000w is a SIZE, not Model #. 4) Have you TRIED to read a 2nd code, by pressing STOP again? Some models can store 2-3 codes. 5) Some models like KY= easy to determine if fuel issue by opening bowl drain screw and checking fuel volume in float bowl or dry/ almost dry bowl?
 
If it runs for a couple of minutes and dies, it's running out of fuel. It either has a fuel pump or gravity feed for fuel. Should be pretty easy to figure that out. Good luck.
 
actually, .002. Regards the fuel supply, with the fuel line to the carb disconnected, running the pump with the priming switch shows a strong flow of gasoline. Well, it did when I was working on replacing the carb. Something could have changed. I'll have to try that again.
 
First, main tank level I never go below 1/2 in case I break down and need to wait w/ heat/ air/ GEN; 2) running 5-7-minutes. especially if surging before dying is typical of a bad/ failing/ intermittent fuel pump. Likely old carb was good. 3) Brand/ Model # on GEN would help? 4000w is a SIZE, not Model #. 4) Have you TRIED to read a 2nd code, by pressing STOP again? Some models can store 2-3 codes. 5) Some models like KY= easy to determine if fuel issue by opening bowl drain screw and checking fuel volume in float bowl or dry/ almost dry bowl?
your advice is appreciated. I'll give things another shot next weekend.
 
My 2003 unit was bought used about 4 years ago, and, for the most part, we've been able to figure out how to use almost everything. For whatever reasons, we never had much need for the generator and neglected it until recently. I began renting the RV out through O------, so I decided to find out how well the generator was working.... oops, it wasn't, Though I had started it once in awhile to show somehow how it was started, I never ran it for more than a minute or two. Suddenly, it wouldn't start. After consultation, I decided the problem was likely a gummed up carburetor...so, I bought a new one (not expensive at all) and managed to install it myself. It immediately started and ran well. Horray! Then a custome decided they needed the generator for a chilly night in the Smokies. Oh, s----! She reported it ran for a few minutes, maybe 5 or 6, then suddenly died. O--"s road service folks suggested the oil level switch was causing the shutdown, maybe, as it is a known weak point, if the unit isn't level and the oil is not right up to the top. That wasn't something she could deal with, where she was, so she altered her plans, put the kids into her sister's house, and ran the RV engine (V10) occasionally to warm the interior for that night. So, on return, I looked it over, started it, and it ran perfectly for about 7 minutes before simply stopping.

A '41' code showed up, No power output. Well, no, there wouldn't be after the engine stopped, would there? I can't tell if the system is sophisticated enough to preserve the actual cause of the shutdown. An on line mechanic basically referred me to the onan manual for that unit and charged me $37. I called the outfit I bought it from 4 years back and they, too, didn't have anything new to add. "Bring it in, we'll probably be able to diagnose the problem in two hours of investigation ($200), but we have got 50 other units lined up in the. yard we need to recondition for sale." I understand.

So, folks, Have Anyone Here Had a Similar or the Same Problem???? What to do to fix it?

I can't say if the problem existed always, because I never really ran it long enough to know.

In the same vein, has anyone abandoned the expensive to fix generator and tried a portable inverter unit? How did that work out?
Biloxword!
Just replace it!
We ended up spending, nearly $2,500 on repairs that didn’t cure the problem!
End result was a new unit.
Your tech will get your permission to change many parts in an attempt to repair your unit. And the normal repair warranty lasts as long as you can see the repair facility in your rearview mirror.
If your plan is to keeping your RV rental business, new is the only way to go. Additionally add a per-hour ly reate for the use of the generator. Put that $$ in a separate account for future repairs.
Mike Root
Saint George Utah
 
You should probably check the troubleshooting section of the owners manual for the genny to see what it says. I'd get ahold of the service manual next to gain further insight and to properly go about repairs.
 
You should probably check the troubleshooting section of the owners manual for the genny to see what it says. I'd get ahold of the service manual next to gain further insight and to properly go about repairs.
i happen to have operator and service manual for it, but so far, I'm still in the dark. lots of good advice here, I'll keep thinking
 
a favor, please. Anyone who has a KY 4000 watt unit in good working order... could you take a couple of snapshots of the linkage on the carburetor and attach them here? I must have improperly reconnected something. I ran it today to see if it was still going 7 minutes then shutting down.... but this time, I kept fiddling with those linkages until, 'snap', something changed position on top of the carb, and it immediately shut down. after two minutes. It starts and runs perfectly for as long as i don't mess with the linkage, up to 7 minutes, when it gets warm enough and 'snap', it shuts down. Pictures, please???

yes, none of my manuals show a picture even of the carburetor, let alone the linkages. I can't locate a Onan assistance board for little generators....
 
Biloxword!
Just replace it!
We ended up spending, nearly $2,500 on repairs that didn’t cure the problem!
End result was a new unit.
Your tech will get your permission to change many parts in an attempt to repair your unit. And the normal repair warranty lasts as long as you can see the repair facility in your rearview mirror.
If your plan is to keeping your RV rental business, new is the only way to go. Additionally add a per-hour ly reate for the use of the generator. Put that $$ in a separate account for future repairs.
Mike Root
Saint George Utah
1978 or so, we were on an rv trip headed for zion or bryce or whatever, and stopped in St George for groceries. I remember how impressive the supermarket was. Nice city.
 

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