Community Forums

Bvandy123 · 06-03-2021, 09:27 AM

Having surging issues on my Onan RV genset 4.0 (BFA 1R/16004C) I read its most likely a carb issue. I have not been able to source a rebuild kit for this carb yet and a new one from onan is like 350 bucks. After some additional research; I found some Chinese knock off carbs that say they fit an onan bfa generator and am wondering if any of you have successfully used a Chinese carb on your onan RV generators. Links would be awesome, thanks!

amosnandy · 06-03-2021, 09:40 AM

Quote:

Originally Posted by Bvandy123

Having surging issues on my Onan RV genset 4.0 (BFA 1R/16004C) I read its most likely a carb issue. I have not been able to source a rebuild kit for this carb yet and a new one from onan is like 350 bucks. After some additional research; I found some Chinese knock off carbs that say they fit an onan bfa generator and am wondering if any of you have successfully used a Chinese carb on your onan RV generators. Links would be awesome, thanks!

You are correct, there is no rebuild kit available for your Onan Carb. I needed one badly and tried ordering a Chineese knock off from Amazon. It wasn't even close. Could not even bolt it on. Mine was the Marquis Gold 5500, so yours may be different. Mine was so far gone there was no repair. If yours runs but surges the first thing I would do is take the bowl off the carb. On the bottom is a knob that you set the altitude with. In the center of that there is a screw, don't remember if it is a Philips or a small nut. CAREFULLY take the bowl loose and see how much junk is in it. Mine was so full the float was shoved shut. Carefully spay carb cleaner up around the float, you can also take the float off and remove the needle seat and clean it up. Do this carefully because you loose one part and you are done. Put it back together, take the fuel filter off and spray carb cleaner in it and fire it on that.

Also, the surging may not be from the carb. On the top of the generator there is a rod that connects to the governor. You may have to take the top cover off to see it. The rod is clipped into a little arm with a nylon snap clip. They break or come loose. If not connected properly the governor keeps surging and turning the throttle on and off. You can buy that little snap clip at any good auto parts store.

Worst case, yes, the Onan factory carb is $350 After hours of messing with mine, I broke down, bought one, bolted it on and it fired on the first crank, ran like a million from then on.

amosnandy · 06-03-2021, 10:38 AM

Quote:

Originally Posted by Bvandy123

Having surging issues on my Onan RV genset 4.0 (BFA 1R/16004C) I read its most likely a carb issue. I have not been able to source a rebuild kit for this carb yet and a new one from onan is like 350 bucks. After some additional research; I found some Chinese knock off carbs that say they fit an onan bfa generator and am wondering if any of you have successfully used a Chinese carb on your onan RV generators. Links would be awesome, thanks!

You are correct, there is no rebuild kit available for your Onan Carb. I needed one badly and tried ordering a Chineese knock off from Amazon. It wasn't even close. Could not even bolt it on. Mine was the Marquis Gold 5500, so yours may be different. Mine was so far gone there was no repair. If yours runs but surges the first thing I would do is take the bowl off the carb. On the bottom is a knob that you set the altitude with. In the center of that there is a screw, don't remember if it is a Philips or a small nut. CAREFULLY take the bowl loose and see how much junk is in it. Mine was so full the float was shoved shut. Carefully spay carb cleaner up around the float, you can also take the float off and remove the needle seat and clean it up. Do this carefully because you loose one part and you are done. Put it back together, take the fuel filter off and spray carb cleaner in it and fire it on that.

Also, the surging may not be from the carb. On the top of the generator there is a rod that connects to the governor. You may have to take the top cover off to see it. The rod is clipped into a little arm with a nylon snap clip. They break or come loose. If not connected properly the governor keeps surging and turning the throttle on and off. You can buy that little snap clip at any good auto parts store.

Worst case, yes, the Onan factory carb is $350 After hours of messing with mine, I broke down, bought one, bolted it on and it fired on the first crank, ran like a million from then on.

mack73 · 06-04-2021, 09:55 AM

I had luck fixing surging on my old generator by running a ton of seafoam through it. Pulled the gas line off and ran it into a small gas can with the seafoam mix.

donr103 · 06-04-2021, 09:36 PM

make sure your armature rings are shiny.. if not you need to clean them.. get back to us and we can tell you how.. it escapes me at the present.. but onan carbs are meant to to cleaned.. you can take to any good mower shop. like john deere shop.. and they can adjust and clean up for you.. they are cleanable on the gen.. take off air cleaner get good carb cleaner in spray can, and look down throat of carb, there are two tiny holes at top, spray in there,, they are idle air, then look for another hole in back at bottom of throat and really get in that.. then fire up gen, let idle down.. put something solid over the carb while running and choke it down then pull off, let run then repeat 2 times..( dont use a rag, it will get sucked in) i like plastic lids off coffee can..it sucks up the crud in carb.. if that does not work.. you have to pull it off and take bowl off and spray out the needle jet.. google it.. some times if you are really good it could be done on the gen but you could loose many tiny parts and that will be bad.. i take mine off.. hands dont work as good as they used too .. before you take carb off.. take good cell ph picts many of them.. count the number of turns you make if you take the needle jet apart and write it down to give you a good base to start.. if yours is lp,, dont do anything i just said..LP is totally different..get back and let us know what you did.. picts of carb would be great.. good luck