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Carburetors, Mixers, Fuel Pumps and fuel delivery Discussion about misc. carbs, mixers, fuel pumps, injectors.

Carburetors, Mixers, Fuel Pumps and fuel delivery

Onan 5kw cck *1977 carb blocked passage PIC


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  #1  
Old 06-16-2015, 01:31:17 PM
RastusM RastusM is offline
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Default Onan 5kw cck *1977 carb blocked passage PIC

Hey all, first post here. Recently purchased a vintage motorhome, and the above mentioned gen-set (only 140 hours on it) will start and run pretty good for about 15 seconds or so, then die. So, I removed the carb, soaked it in Berryman carb solvent, did the wire down the orifices trick and then blew out the passages with 140lbs of air, with a rubber grommet, and finally added two fuel filters. The result was, no change whatsoever, exact same symptoms which was a surprise because the carb had allot of dirt in it. So, my question is, as you can see in the image, there is one passage indicated by my oh-so subtle arrow, that passageway is blocked by something. All other passageways flow freely except that one and it's blocked really solid. Am hoping someone can tell me for sure, that that passage is really supposed to be open and isn't a factory blind hole? It clearly bottoms out hard and seems like a blind hole to me, I'm just trying to rule out this carb as the problem and move on... or fix/replace it. Thanks for any help here.
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Old 06-17-2015, 05:16:18 PM
mmcdonald mmcdonald is offline
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Default Re: Onan 5kw cck *1977 carb blocked passage PIC

That hole and the one symmetrically to the left of it are idle air circuit passages made in all the castings of the marvel schebler VD. The casting has two of them but only one will be completed that is above the idle needle. I can't tell where the idle needle is on your picture so I can't say for sure. For instance if your idle needle is on the right side of center per the picture then that hole does keep going to the idle needle area(but I don't remember off hand if it changes dimensions). If your idle needle is the left of center per the picture then the passage on the left would be completed to the needle area and the right does not lead anywhere. Good luck.
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Old 06-17-2015, 08:53:57 PM
RastusM RastusM is offline
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Default Re: Onan 5kw cck *1977 carb blocked passage PIC

Wow, no kidding? That would explain allot and you have no idea how hard it was to find that little jewel of information, so.. as my grandpa used to say "thanks a million". Btw, the issue I'm having with the onan generator is it will start up and run for a bit, then quit. I've had the carb off for cleaning twice with really no change in symptoms. I believe the culprit is a deteriorated seal on that screw that comes up through the float bowl, that would be the air adjustment screw, correct? It's seriously deteriorated, could that be causing these symptoms? Thanks again.
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Old 06-17-2015, 09:57:43 PM
pegasuspinto pegasuspinto is offline
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Default Re: Onan 5kw cck *1977 carb blocked passage PIC

The screw you describe on the bottom is the main jet.

You need to find out why it quits. Does it make AC power when it runs? Does it stop like someone turned it off or does it sputter to death? Put a test light on the coil and see if it loses power when it dies. If it's running out of fuel, a fuel flow test is in order. IMHO you don't have a carb problem from how you describe it.
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Old 06-17-2015, 11:31:37 PM
RastusM RastusM is offline
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Default Re: Onan 5kw cck *1977 carb blocked passage PIC

Yes it makes power, runs the AC above my head when it fires. Well, the seal on the main jet is complete toast, might as well not even have one... it went into the carb solvent tank, yes, oops. No it doesn't die like spark is being cut, sputters and I can make it run by messing with the throttle. That little seal, can I use a rubber o-ring or does it have to be that fiber asbestos camel hide, whatever it is- oem?

---------- Post added at 10:31 PM ---------- Previous post was at 10:25 PM ----------

I know of an 89 Marquis 5KW with 150hrs on it... 350$... I'm "sorely tempted" since the choke is inop on this ol' girl too. Any thoughts?
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