More Onan 2.8KW questions - carburetor

[backbencher]

Hi folks. Just got back from one of Uncle's mandated trips to lovely Kuwait, and so of course the '01 Dodge Roadtrek has been sitting idle, inexpertly stored by my buddy (for free, mind). The fridge is full of mold, the shower faucets need replacing, etc. The problem I come to y'all for is the generator carburetor.

The gen runs. Here's how to get it started in cold weather. Make sure the van is dead set level. Start it. It dies. Wait 25 seconds, start it again. Do this for 15 minutes, and once it runs past 1 minute, start adding loads - fridge, electric heater, laptop, etc. Then it will run for hours - occasionally it will drop when a load kicks on, but will start right back up.

Local RV dealer (not Roadtrek) says the carburetor is a sealed 50 state unit from Onan, and they can't even spray carburetor cleaner in it. All they can do is replace it, which after 3 hours of labor to drop & reinstall the generator, comes to nigh on $1K.

So what do y'all do? Keep in mind I'm a full timer w/ limited tools - anything I do is pretty much in someone else's parking lot, unless I can go to the Navy base & use one of the Auto Self Care bays.

[Handbasket]

For those who're wondering... yes, the 2800 Microlite has an electric fuel pump. Taking the service access panel as the front, it's buried in the left rear corner. No access without taking the green top off of the box. If you've got the service manual, you can maybe sort out which lead in the big bundle coming off the voltage regulator powers it. Then it'd be fairly easy to splice in a switch.

If you're in a dry desert place, fine. I personally wouldn't do it in the humid SE. Too much condensation forming in the electrics that needs monthly running to drive off. I've even read one post on usenet about a 2800 that had the rotor & stator corroded so badly that it was locked up. There's also the copper rings of the commutator that may corrode and cause issues.

Yes, the carb on the 2800 is a non-rebuildable. I've never heard of one being replaced without the green box top being off, so it has to be dropped out from under. A shop would probably bill 3 hours to do the job, 5 bolts, 4 or 5 wires, fuel line.

The DIY alternative to replacing it, if it'll start at all, is to cut the fuel line somewhere forward of the Onan and drop it into a gas can with a heavy dose of Techron or Seafoam. Run it long enought to get the mix in the carb, let it sit overnight, run again to freshen the solvents in the carb. Repeat daily. If it doesn't run smoothly after a week of that, it needs a new carb.

Jim, "Never try to outstubborn a cat."

[Horizon170]

https://www.prvparts.com/ProductDetails.asp?ProductCode=41793$1,000.00 is way too high. Less than 300 bucks shipped and 100 to put it on or install yourself.
Any time I can do the leg work it saves me money.

[scarpi]

backbencher wrote:

Local RV dealer (not Roadtrek) says the carburetor is a sealed 50 state unit from Onan, and they can't even spray carburetor cleaner in it. All they can do is replace it, which after 3 hours of labor to drop & reinstall the generator, comes to nigh on $1K.

backbencher, I have an Onan 2800 on my 09 Pleasure Way and I had to have the carburetor replaced. A local RV parts/repair shop charged me $432 to replace the carburetor and change the oil. You price of about $1000 is very high to replace the carburetor.

[mlts22]

My Roadtrek wrote:
I wish the manufactures would offer a fuel cut off to the generator. If I lived where I couldn't run my Class B I would put one on and just run the carb dry. My power washer has one and I never had a problem.

x2. One of the reasons I've had so little trouble with my Yamaha generator is that I turn it off at the fuel petcock, so the carb runs itself dry before storing it. It would be nice to have, at least, a manual valve, or a valve that uses a solenoid so one can remove electrical loads from the genset, flip the fuel switch off, and let the generator run all the gas out of the lines before putting the MH into storage.

[Horizon170]

I'm not sure if the 2800 has a fuel pump but I installed a toggle switch to cut off the pump on my Onan 6.5K so I could run the carb dry.

[PCarnathan]

My Roadtrek wrote, in part:
"I wish the manufacturers would offer a fuel cut off to the generator. If I lived where I couldn't run my Class B I would put one on and just run the carb dry."

I think that's a great idea, too. I'll have to climb under there again and see if there's enough room in the fuel line to install such a valve.

Good plan...

Pat in Menifee, CA
www.patcarnathan.com

[My_Roadtrek]

I wish the manufactures would offer a fuel cut off to the generator. If I lived where I couldn't run my Class B I would put one on and just run the carb dry. My power washer has one and I never had a problem.

[truepath]

I live in Minnesota and it is not practical to run the generator once a month given very low temperatures. Instead, late in the fall I will add a can of Sea Foam (fuel stabilizer) to the RV gas tank when the tank is almost empty and then I run the generator for an hour or so. The gas left in the generator carb is, therefore treated. I start the generator several months later and I have not had an issue, except it does take a while to start it the first time in the spring. I do the same thing (add stabilizer) with all of my other small engines at the change of seasons and this has worked for me for decades.

[Fastpaddler]

Put Stabil in gas tank if rv is sitting unused for a long while. It inhibites grunge/varnishing of carb and in fact it must work cause my 2 previous gas gensets ran great although they tended to be slow starters when unused for a while. My LP one with the PW runs great all the time.

[PCarnathan]

I've had a couple of Onans. We had a 5500 in our 5th wheel, and now the little 2800 in the Roadtrek. Obviously, there are other generator options out there. A lot of folks are perfectly happy with one of the Honda suitcases. I inherited my Roadtrek. When I took ownership the generator would idle, but it wouldn't run under a load. I bought the carburetor locally and installed it myself. Dropping the generator from under the van is only slightly difficult because the wiring has to be dealt with. Use a floor jack to roll the generator out from under the van, replace the generator and roll it back under.

You can't blame Onan because the carburetor gets damaged by fuel sitting in it. Running the generator every couple of weeks (under a load) is another part of RV maintenance. This applies to any number of other small engines. Lawn mowers, trimmers, snow blowers, chain saws, etc. When gasoline sits for a long time it will go bad unless you use a stabilizing agent.

Pat in Menifee, CA
www.patcarnathan.com

[My_Roadtrek]

If your A/C is an 800 BTU you will need at least a1600 watt gen-set to start it. Good rule of thumb is to double your A/C BTU's to determine the size of the generator needed to start it.
Onan's are very good generators, and will give good service for many years if maintained properly.

[backbencher]

Well, the generator is actually running now, charging the engine battery - left the headlights on : ( I think Onan has convinced me to never own another Onan. I'll run some carburetor cleaner through the gas tank, and probably get a 2 stroke Harbor Freight for $88.88 and call it good. I've run the A/C in a Texas summer off one of those little Chinese gennys, and if it will fit in the basement, I'll get a couple of small NATO gas cans & carry them down there. Then if the gen won't start, the little 900 watt 2 stroke will.

[PSW]

Backbencher, sorry for your Onan problems. This is a very cautionary tale for all of us, particularly given the bad weather all over the country and the subsequent low or no useage of our RVs. Exercise, exercise, exercise. It is a pain for me to get mine out in the cold and run the genset for an hour at least every month.

I do and your post reminds me that I MUST do it. I drive up the interstate to a little town with a good hamburger joint, about 25 miles up the road. I run the genset on the heat pump setting and leave it running while I eat my burger. That gives the coach 50 miles and the genset an hour and a half or so, under constant load.

I get tired of this little doings, but your post sure made an impression on me and I again I am sorry for your problems.

I read Handbasket's comments My Roadtrek posted above and the link Horizon170 posted. Good suggestion for you and all of us.

[Horizon170]

I found this on another
http://toyotamotorhome.org/forums/index.php?showtopic=4444

Edited to make link active.
To make a link active yourself just use the Link icon at the top of the message box. Blue/green orb with the picture of a link.
Thanks

[My_Roadtrek]

The carb can't be rebuilt, and you have to drop the gen-set to replace it.
Some members have had some success with running Sea Foam through it, It's worth a try, but I wouldn't get my hopes up to high.
Here is a post by Handbasket from a few years ago. He's still on the forum so you can PM him if you have questions.
On edit, just getting the fuel filter off is a real pita!
"
Posted: 01/05/04 03:25pm Link | Edit | Print | 13209874 | IP
For those without the time or inclination to read my ramblings, let me just say, "Believe the Onan manual! Run your genset every month! It's a b!t$h to get to on a B van, at least a Roadtrek, and is likely to cost major money if you let the gas sit in the carb." If you haven't looked, it sits in a box under the floor, only accessable thru an access plate about 8" x 15" that is wholly inadequate to work thru. Let my tale of misery be a warning! That's all.

(Warning!! The rest is long and boring!)

OK, so when I bought my new-to-me '02 Roadtrek back in the early Fall, I screwed up. The gas tank was almost empty, so we couldn't run the genset. "No problem," thinks I (bad case of wanna new van fever), "Onans 2.8's are pretty reliable, and this thing is close enough to new that I'm sure it just needs gas. It'll be OK...."

Yeah, right. 8,500 miles on the clock, 1 1/2 years old, 29.5 hours on the genset. I really didn't think about how long it had been sitting idle on the consignment lot, or with the PO, with no exercise.

Well, it wouldn't start. Cranked OK, but no fire. So I got under and took of the access plate. Still couldn't start it using the button underneath, until I figured out the choke linkage and diddled it by hand every time I wanted to start it. Then it loped like crazy, with the revs hunting up and down, up and down, cycling about every three seconds. Putting _any_ electrical load on it killed it immediately. I tried a can of fuel system cleaner, with little result.

We finally had some warm weather over the weekend, so I tackled it (don't think Onan would honor the warranty for neglect). Adjusted the choke first (this is why this is in the B van forum, instead of the tech issues forum).... dam', that's a poor design!!! You go thru the access plate at the back, and have to hold the 7 mm wrench in your bleedin' fingertips to reach the two nuts! Don't drop the wrench; it'll go out of reach in the tray under the generator! I _had_ 3 7mm wrenches; now I have two.... Why couldn't they make the access plate full width???!!! Second try got it right, and it starts fine, but still lopes...

So, yesterday, I tackled the carburetor... again, very poor design as far as service access. Fuel filter has to come off, housing is in the way of the lower hose clamp, etc.... I'm not sure you can pull the carb without dropping the whole thing out of the vehicle. It doesn't look like it. I settled for taking the float bowl off and spraying some carb cleaner in there, and filling the fuel filter with gas treatment.

Still lopes, but not as badly; occasionly smooths out entirely for a inute or two. Definitely some varnish in the carb from sitting. But now starts, runs, and even accepts a load sometimes. Making progress. Even ran the heat pump briefly.

So today, I dosed the gas tank with two varieties of cleaner (Techron and Sea Foam) and drove around to mix it up. I then ran the genset long enough to get it thru the system. I plan to start and run it every day for while to keep fresh cleaner in the carb, hoping to dissolve the last of the varnish that way. I'd really rather not drop the genset box....

Dunno if it'll work. But I want anyone who read this far to remember to exercise your generator!!!