Forum Discussion

IDoMyOwnStunts's avatar
Feb 21, 2016

2014 Onan 4000 fuel leaking from carb

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.

17 Replies

  • Most likely you have some trash in the carb. Clean it out and you will be ok.The one hour a month rule. Is to try and prevent varnish build up you get with the new gas. Depending on where you live. The gas can go bad fast.Storing it for over thirty days can cause problems.
  • I'll get a model number. I'll have to wait until next Friday since I'm working all this week. I store it undercover at a friend's house who has acreage, so it's not as simple as walking outside my house.

    I topped the gas tank in August, which is 6 months. The previous top off was in April. I filled about 1/2 tank in August but I'm not sure how much I filled in April. Probably not much, unfortunately. I'd like to offload all the gas, but have no idea what to do with it. 30 gallons worth in a 40 gallon tank. That would take forever to burn through in a lawnmower. I just know I don't want to use it in my truck since I have direct injection. If I cut it with some new gas (say a 1:1 ratio), do you think it might be ok for an older truck? My friend has an 03 V-8 Dakota and he's said he would be willing to use the gas up, but I don't want to mess up his engine too.

    I got the unit in August of 14, so I thought 18 hours was right on schedule doing 1 hour a month. Instructions say to run 1 hour a month with 30 minutes loaded. Last ran in January. Going forward, I'm not going to put nearly so much gas in the toy hauler unless I'm positive I'm going to use it.

    I might already have the torx bit. I do have the socket. I will have assistance this weekend. It's kind of funky because the carb is in the side. I haven't encountered an engine like that. I'm used to auto engines.

    My plan is that I'll first use an inspection mirror to look inside carb and see if I can spot anything obvious. I'll get the manual out as well and take pictures of the linkages before I do anything. Then I'll try "tapping" the bowl first. If I get it running, I'll load it and run it for a few extra hours. If it still doesn't run and I think I can get it off, I'll do that next. If it looks beyond my skill, I'll just take it to the shop. I looked up Onan repair shops from a previous thread I found and it looks like there is a shop much closer to me than the Wood Village Camping World.

    Thanks for the advice. I appreciate it. At least I now know where to start. I'll update this later.
  • 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.
  • j-d's avatar
    j-d
    Explorer II
    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.
  • 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.
  • 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
  • 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