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Onan issue [message #135221] Tue, 19 July 2011 15:47 Go to next message
Rickmo is currently offline  Rickmo   United States
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Registered: January 2011
Location: Gladwin, Michigan
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Well my buddy brought his GMC over for me to work on -- the joy! His 4000 onan runs great without a load but when you put the roof air on, the Onan starts to run rough and eventually quits. It acts like it is getting too much gas/smelly and smoking. If I try to rev it up by manually operating the throttle it does not really help. I am thinking that the carb is needing attention. What are your thoughts?

Rick Seebeck Gladwin Michigan 1973 Canyon Lands

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Re: Onan issue [message #135249 is a reply to message #135221] Tue, 19 July 2011 19:09 Go to previous messageGo to next message
jim kanomata is currently offline  jim kanomata   United States
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Registered: March 2007
Location: fremont,ca
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Did you try richening the secondary

Jim Kanomata Applied/GMC, Fremont,CA jimk@appliedairfilters.com http://www.appliedgmc.com 1-800-752-7502

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Re: Onan issue [message #135289 is a reply to message #135221] Wed, 20 July 2011 06:18 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
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Rickmo wrote on Tue, 19 July 2011 16:47

Well my buddy brought his GMC over for me to work on -- the joy! His 4000 onan runs great without a load but when you put the roof air on, the Onan starts to run rough and eventually quits. It acts like it is getting too much gas/smelly and smoking. If I try to rev it up by manually operating the throttle it does not really help. I am thinking that the carb is needing attention. What are your thoughts?

Rick,

It is probably just the mixture. Adjust the main jet. If you don't know where that is, go to Bdub's manuals and download it.

Don't ever move that more than 1/4 turn at a time.

Matt

Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

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Re: [GMCnet] Onan issue [message #135306 is a reply to message #135289] Wed, 20 July 2011 07:53 Go to previous messageGo to next message
Jim Bounds is currently offline  Jim Bounds   United States
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Registered: January 2004
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Also, the changes in the motor from adjusting the fuel mix screw on the float
bowl lags the event somewhat so turn it a bit and wait to see what the generator
does.  I also think it's a fuel adjustment issue.  It could though be a case
that the carb is corroded inside and the aluminum of the casing is pitted
allowing too much fuel to bypass the needle.  This is the #1 reason to put down
the carb which will usually put down the generator because finding a good carb
is difficult.  Could also be points adjustment, try that too.

Jim Bounds
----------------------



----- Original Message ----
From: Matt Colie <matt7323tze@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Wed, July 20, 2011 7:18:37 AM
Subject: Re: [GMCnet] Onan issue



Rickmo wrote on Tue, 19 July 2011 16:47
> Well my buddy brought his GMC over for me to work on -- the joy!  His 4000 onan
>runs great without a load but when you put the roof air on, the Onan starts to
>run rough and eventually quits.  It acts like it is getting too much gas/smelly
>and smoking.  If I try to rev it up by manually operating the throttle it does
>not really help.  I am thinking that the carb is needing attention.  What are
>your thoughts?

Rick,

It is probably just the mixture.  Adjust the main jet.  If you don't know where
that is, go to Bdub's manuals and download it. 


Don't ever move that more than 1/4 turn at a time.

Matt
--
Matt & Mary Colie
'73 Glacier 23 Chaumiere (say show-me-air)
SE Michigan - Twixt A2 and Detroit
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Re: [GMCnet] Onan issue [message #135308 is a reply to message #135306] Wed, 20 July 2011 08:18 Go to previous message
George Zhookoff is currently offline  George Zhookoff   United States
Messages: 398
Registered: December 2004
Location: Snellville, GA
Karma: 6
Senior Member
It could though be a case
that the carb is corroded inside and the aluminum of the casing is pitted
allowing too much fuel to bypass the needle.  This is the #1 reason to put down
the carb which will usually put down the generator because finding a good carb
is difficult.  Could also be points adjustment, try that too.

Jim Bounds
----------------------






  It acts like it is getting too much gas/smelly
>and smoking.  If I try to rev it up by manually operating the throttle it does
>not really help.  I am thinking that the carb is needing attention.  What are
>your thoughts?

Rick,

It is probably just the mixture.  Adjust the main jet.  If you don't know where
that is, go to Bdub's manuals and download it. 


Don't ever move that more than 1/4 turn at a time.

Matt
--
Also check fuel adjustment needle O ring. It's 1/8 X 1/4.

George Zhookoff
78 EL II
Atlanta

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