I have an Onan 4000 generator on my Shockwave. It's always been a little finicky to start. However, this past week when I went to start it for the monthly run, it just would not catch. I noticed fuel leaking out of the air filter cover (through the air filter), so I assume it's coming from the carburetor. It's pretty new (2014), but I suspect it's flooding out. I did put Stabil in the tank and the fuel was topped off in August of last year. It has 18 hours on it, mostly from maintenance runs.I didn't have too much time to mess with it then. It's still under warranty, but I really dread having to drop it off at the dealer. They took months with my last unrelated repair and I have a horse show to go to in a couple of weeks. I also suspect that if it is clogged/gummed up that it won't be covered.So, my question is, can I just take this carburetor apart and clean/inspect it? I've heard they are one piece units now. Any suggestions? I can live without it for now (I have solar and I won't be dry camping), but I'd rather fix it myself if I can. Thanks.

Most likely a foreign object lodged in the needle/seat float shutoff. If possible, remove the bowl from the carb. Then drop the float w/ needle and clean. This may not be possible on newer models, and in your case

Stunts, So much here depends on the shop doing the warranty. If it is an RV dealer, that may be a problem. Most hate doing any warranty as it doesn't pay well and then it takes forever to get that. If you can get the carburetor off without showing any damage, do it. Clean the needle and seat and put it back together. If that doesn't get it, then take is somewhere and be ready to call or drop by every other day after the first week and every day after that first week. Don't be afraid to suggest that the shop call Onan.Don't be afraid to call Onan. Don't hesitate to get Onan/Cummins involved. They have a reputation and a price point that they try to maintain. That is what I would do. They might not like it, but it is the job that they signed up to do. Matt

Onan stated years ago. They will not cover under warranty. Carb repair or replacement. Due to lack of use.An almost two year old unit with 18 hours is lack of use.

When was the last time you ran this genset?You topped the gas tank nearly a year ago. How much gas and how old was already in there? I think you're past the time span where StaBil will protect you.Is this ONAN a 4KY-something? Always post the Model Number and Spec Code. Ours, for example, is Model 4KY Spec K.If you have a 4KY, it's "possible" to get the float bowl off without removing the carburetor. You have to separate some wiring to even start and it's a slow go with a wrench on the bowl "nut." Not all that bad to remove the whole carb, but you need a T30 Torx bit, a 10MM socket and a lot of patience. ABOVE ALL you need pix and drawings of how the Throttle and Choke linkage, plus a little Spring on one of them, fall in place. Fail to do that and you'll be miserable. If you take the float bowl off, you should be able to clean Needle and Seat. More likely, the float pivot stuck in the dropped position and you can clean that. Then... IF you've been running it regularly and it ran OK last month or so, you may get it running again and dodged an expensive bullet. Those carbs are around $200 and so difficult to clean the idle passages that many of not most just get replaced.

You could try the "old days" method,.....beat on the bowl. I didn't say that !!But in reality, tap on it, could just unstick something that mite be stuck.

2014 Onan 4000 fuel leaking from carb | Good Sam Community

NinerBikes
Explorer
Feb 23, 2016
TEXAS wrote:
As I said it depends on where you live and the blend you have. I have seen gas down here go bad in 30 days. I have pulled carbs apart that had stuck floats or needles stuck. Also have seen just trash clogging one up.

The fuel I get here in Los Angeles from November through March is problematic with in 45 to 60 days. Summer fuel is much better. The stuff I buy in ID or MT is good for up to 2 years or more, straight gas, no ethanol.
IDoMyOwnStunts
Explorer
Feb 27, 2016
I got the model number from it. 4kyfa 6747p

Due to the weather, I really didn't get a chance to do anything with it yet.
IDoMyOwnStunts
Explorer
Mar 28, 2016
Just a quick update. I was able to mix in about 6 more gallons of fresh gas into the tank. That got it running, but it only ran for a couple of minutes, sputtered, then died. The exhaust was white, but not smokey. This was repeatable after I let it rest for a few minutes between. It wants to run, which is really the frustrating part. It certainly seems like it's getting gas. After each run and die cycle, there's still gas in the carburetor bowl. I'm thinking there may be water in the gas. I'm going to offload what's in the tank and try again with fresh gas, just to eliminate that possibility before I mess with the carburetor any more.

Couple more questions. I keep reading about seafoam, mostly from those who think it's the bee's knees. I'm reluctant to put something that "cures everything" into the tank. Any opinions?

And what in the heck am I going to do with 30 gallons of potentially bad gas? Any ideas? It's in a toy hauler, so I have a fill station.

I may still end up taking it to a mechanic.
RJsfishin
Explorer
Mar 28, 2016
Does the carb have any altitude adjustment etc ?
We had an onan a few weeks ago that was "hunting" badly. I messed w/ the altitude adjustment, fixed it, and at last report is still running fantastically.
If the gas smells like normal gasoline, its not bad. Or dump some in your lawn mower, prove its not bad gas.
IDoMyOwnStunts
Explorer
May 11, 2016
Update: Offloaded about half the gas in the tank. It ran fine through my wife's Jeep (split it half with the toy hauler gas and half a tank of fresh gas). Also offloaded some to my friend's Mustang. No issues with either. Lawnmower and chainsaw burned it fine too. Still, we put about 8 gallons of fresh gas back into it.

So we got it running and it came up to speed fine. Seems the warmer weather and fresh gas did it some good. But, while it was running it started blowing white smoke out of the exhaust. Shut it down, checked the oil, and it spewed out of the fill/dipstick port. Looks like it somehow got a lot of fuel in the oil. Drained it out and replaced the oil, but ran out of daylight. Hopefully no permanent damage was done, but we (my friend and I) are still working on it.
IDoMyOwnStunts
Explorer
Jun 26, 2016
Update: Something's really screwed up, so I'm just shutting it down and taking it to a professional. I've got a bad feeling about this.
s99klein
Explorer
Aug 21, 2020
I'm curious what you finally figured out with your generator. I'm having a nearly identical situation with mine. I've replaced all fuel related things - pump, filter and carb and still have fuel pouring out of filter. It will try to run but die and fuel pours out of filter. Perhaps my after market pump is too strong? Is there something else you found out? (I know this was a while ago, but can't seem to figure this problem out.

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2014 Onan 4000 fuel leaking from carb

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