| [GMCnet] Onan runs like Sheet: Episode II, the Onan still runs like sheet [message #80309] |
Mon, 12 April 2010 12:28  |
fbhtxak
Messages: 191
Registered: April 2006
Karma:
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Senior Member |
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Shan,
If you still have the OEM breaker point ignition system, I
recommend you try a replacement ignition capacitor. A few
years ago, I had problems similar to those you describe with
the Onan in my AirstreamMh/Alaska. I concluded that fuel
delivery was OK as, without a load on the generator, the
engine operation was normal (although starting was sometimes
difficult).
I had changed the points/condenser only about 5 hours
earlier. The spark plugs looked normal. After clearing fuel
delivery, ignition points/capacitor and spark plugs as
causes, I borrowed and installed a known-good replacement
coil. 'Had no effect. Since the genset operated normally
before I changed the ignition points/capacitor, I decided to
reinstall the capacitor I removed 5 hours earlier. End of
problem!!
Why did the new capacitor not work? 'Discussed this with an
Onan engineer who is member of our local GMC Classics group.
He said this is a relatively common problem with "new" Onan
capacitors. They, however, are really NOS (new old stock)
and are prone to deteriorate with time. When there apparent
ignition problems after ignition point/capacitor change-out,
he recommended exchanging the capacitor for another one (or
install one removed when the genset was operating normally).
I did the latter as I was 100 road miles from a Cummins/Onan
dealer.
I do not know a way to conclusively check a new capacitor to
be sure it will work.
Fred Hudspeth
'78 Royale - Tyler, TX
'82 Airstream Excella 28' Motorhome - Anchorage, Alaska
Message: 13
Date: Sun, 11 Apr 2010 11:49:13 -0500
From: Shan Rose <defconfx@gmail.com>
Subject: Re: [GMCnet] Onan runs like Sheet: Episode II, the
Onan still
runs like sheet!
To: gmclist@temp.gmcnet.org
Message-ID: <13917.4bc1fd88@gmc.mybirdfeeder.net>
Content-Type: text/plain; charset="ISO-8859-15"
Ok, first off thanks for the imput guys, I'm stil leaning to
a carb/ignition problem however. I dont think the heads are
carbonized really tha much, reason being when I pulledthe
plugs for a plug reading they were a nice light tan, not
sooty black, and I have had the onan run for many hours and
it always ran like a clock, only with an occational sumble,
and I would load the SOB down with a good 30 amps of load,
and it would chug away with no problems.
then one day it just started acting like that, and then
wouldnt start. also the fuel mixture smells richer then it
should be, and there is not an occational backfire, the
report something akin to a 1911 .45 ACP, which is real fun
when you dont have your ears on. while working on the onan I
take my rig to a commercial/industrial area as to not get
the attention of the police looking for someone discharging
a firearm within city limits.
Also ther still the odd EM feild whcih seems to like to
screw with sensitive digital equipment. it was causing the
display screen on my expensive sony HD handy cam to jump
around when my GF got to cloose to the genset running.
As for Carb Icing, well its more of a clod sweat, the air
temp yesterday was about 68 degrees when I was making that
video. but you can see the sweat on the intake. its like the
cooling effect seen with top fuel or nitrous injection. so
this is what is making me think perhaps the onan is
inhailing a denser mix of fuel then it should. it would seem
its not atomizing correctly for some reason. and for what
ever reason, walbro does not include a new power nozzle with
the rebuild kit for their carb.
now as to what makes me think it could be ignition related
is the strange EM feild which I never witnessed in my onan.
it also screws with my digital timing light, something which
it never did before.
basically what I need is someone who can loan me a working
old coil or spare carb to troubleshoot both of these
systems. I'd take care of the shipping and return. I need to
get this onan running right, I do a lot of dry camping and
need my AC 120 to effectively do stuff...
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