Onan microlite 2800 Gas Carburetors

Seafoam may or may not "work" but it should not cause harm..

The problem is that just sitting the carb in a vat of any cleaner including Seafoam often will never make it to where the clog is..

The gas could be treated with some Seafoam and allowed to run then shut down for a day or two between runs might help clear a partial obstruction but will not help at all for a full obstruction..

Now, to complicate things abit, there are two types of carbs, gravity fed (tank above) and fuel pump fed (tank below carb).

The link I gave assumes gravity fed, Onans due to the fact that most pull fuel from a tank lower than the carb often will use a fuel pump..

Sometimes the fuel pump is built into the carb operated by the vacuum created by the air moving through the carb body.. Many Briggs engines use that and they call it "pulsa jet".. With that there is a fuel pump diaphragm built into the carb that over time wears out or hardens..

Onan may or may not use that, if they do, unless there is aftermarket manufacturers making that diaphragm you are out of luck..

If Onan is using a external vacuum diaphragm pump (separate pump with a vacuum hose that goes to carb vac port), you may be able to find replacement pumps..

Some may use an electric fuel pump which may be possible to substitute with a low pressure aftermarket auto fuel pump designed for old school carburetors (not fuel injection).

The reason I brought this up is if the fuel pump is weak, your carb may be running out of fuel and hunting causing your symptoms..

But a good cleaning of your carb should not cause problems and is a logical step to trouble shooting instead of simply replacing parts..

If you can get the carburetor off then soak it in SEAFOAM for 24 - 48 hours or a quality carb cleaner.
Retry

jltarley wrote:
I've recently purchased a 1988 RV with an Onan KV spec J 2.8 gasoline. I was able to get the generator running, but it runs rough, and surges very strongly. All research leads me to believe that the carb needs replaced.

The carb in the generator is P# 146-0861. I've had a hard time finding a replacement for less than $300, and there just does not seem to be a lot of them out there. I have been able to find quite a few 146-0569 carbs, which are from previous versions of the same model gen.

Are these carburetors interchangeable? If not, does anyone have any other good solutions for this issue?

There is most likely no "direct fit" carb available, some like Onan are proprietary to that manufacturer.

Now, if you are extremely handy with wrenches, have a good shop full of metal working tools like lathes and milling equipment it might be possible to "fab" your own adapter to a small engine carb like a Honda.

Then the problem there is figuring out how fuel gets to the carb, is it compatible with the fuel pump used, the linkages work, getting the throttle to work with the governor and the proper RPM of the engine.

Now, about this time your are thinking that all is lost..

Perhaps, you should think about trying to CLEAN the carb first before declaring it dead..

Many small engine carbs use a similar setup which uses what is called a "jet", the jet meters the fuel that is taken into the carb throat.. The jet gets clogged and now the engine may run ruff or not at all..

Many small engine carbs you can remove the fuel bowl and access the jet to clean it with spray carb cleaner.

See PAGE 3 IN THIS LINK where I tell how this can be done on a Honda GX series carb which might be helpful to you to figure out if the Onan carb can be serviced.. There is a link to some You Tube vids that may prove helpful..

If your Onan carb has similar design, you might be able to disassemble and clean the jet for the price of your time and a can of carb cleaner..

I hate this "throw away" mentality that is prevalent now days..