Good Sam Club Open Roads Forum: Onan 4000 -Carb replaced - now idle is high (Code 14)
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 > Onan 4000 -Carb replaced - now idle is high (Code 14)

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Baja Man

Inland Empire, CA

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Posted: 11/12/20 03:00pm Link  |  Quote  |  Print  |  Notify Moderator

I had surging that would not go away after I used fresh fuel and Seafoam. Genny has 152 hours and previously ran fine. Fuel pump does pump adequate fuel, new plugs, oil changed, new fuel and air filters.

Decided to try a new carb from Amazon....

Installed and started.

RPMs are high and genny will shut down and indicate code 14 which is Over Frequency Fault.

There was light white smoke from exhaust when it did run.
I did make some adjustments to the two screws that sit at the right middle/rear of generator. Screwed them in and out. Made no difference.

BTW....the new gaskets were a pain to install (longest part of installation) as the right side of carb (intake manifold side) uses a 1/2" plastic plate and a gasket on each side of plate and also the lefty side has a gasket between carb and air cleaner frame. Not much room between air cleaner frame and intake....you have to slide the gaskets in place, lining up hole pattern to carb.....all while making sure the 4"-5" carb mounting bolts go through all of these pieces!!!

I could have missed something...gaskets no seated properly allowing air, linkage not properly adjusted, etc.??????

Not sure where to go from here.

Thoughts?

* This post was edited 11/12/20 04:37pm by Baja Man *


2003 Ford F-350 XLT Super Duty, Crew Cab, V10 (6.8L); 4X2; Standard Bed; SRW; 4R100 trans
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Flute Man

Payson, Arizona

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Posted: 11/12/20 09:47pm Link  |  Quote  |  Print  |  Notify Moderator

I would think that there would be some linkage out of the governor to the throttle positioner on the carburetor where the speed could be adjusted. Maybe by changing the carburetor you influenced this adjustment.


Jerry Parr
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Baja Man

Inland Empire, CA

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Posted: 11/13/20 09:08am Link  |  Quote  |  Print  |  Notify Moderator

I'll double check linkage and see if any errors in my install. I believe I installed just as it was with OEM carb.

NOTE: I tried the Amazon carb with the chance I would get a good one.....but as the saying goes....you get what you pay for!!

If I am unable to fix, I will have a new Onan carb installed.

Flute Man

Payson, Arizona

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Posted: 11/13/20 08:10pm Link  |  Quote  |  Print  |  Notify Moderator

I would think there would be a speed adjustment somewhere so that you could dial it right in.
You would probably have to use a frequency meter to adjust. I would check with Onan to get their recommendations and procedures.

RJsfishin

Winston Or.

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Posted: 11/14/20 06:34am Link  |  Quote  |  Print  |  Notify Moderator

First thing I would do is put the original carb back on. At 152 hours , the carb is like new yet, and surging is not a reason to change out a carb.


Rich

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Baja Man

Inland Empire, CA

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Posted: 11/14/20 08:02pm Link  |  Quote  |  Print  |  Notify Moderator

Update....

I could not get idle to settle down.

So......
Took it to an Authorized Onan repair person today (took me in on short notice and only 45 min from home). Installed a new OEM Onan carb and then found that Governor rod had become stuck and way out of adjustment. Cover had to be removed to access governor linkage which is at center/rear of generator.

He adjusted linkage rod and also set RPM and frequency to exact OEM specs using a digital frequency/voltmeter. Apparently this procedure is used to adjust the governor to bring frequency and voltage within the specified range, and to set governor stability.

All is well now..... it runs better than it ever has!
AC and microwave both on and it runs smooth as silk!

I'm a happy camper!

* This post was edited 11/17/20 11:06am by Baja Man *

Flute Man

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Posted: 11/16/20 02:10pm Link  |  Quote  |  Print  |  Notify Moderator

Glad you got it fixed and thank you for posting the solution.

Jerry Parr

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