| Onan, Backfire [message #163783] |
Wed, 21 March 2012 20:08  |
MikeT
Messages: 225
Registered: November 2009
Location: Marine City, Michigan
Karma: 0
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My 6K Onan purrs like a kitten. The other day I shut it down and it backfired. Scared the you know what out of me. Today I started it up and it backfired during start up and then started and ran great.
Any suggestion on what is going on or how do I fix?
Thanks
Mike Thomas
Marine City, MI
77 ex Palm Beach
[Updated on: Wed, 21 March 2012 20:09] Report message to a moderator |
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| Re: Onan, Backfire [message #163795 is a reply to message #163792] |
Wed, 21 March 2012 21:34  |
MikeT
Messages: 225
Registered: November 2009
Location: Marine City, Michigan
Karma: 0
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Matt, only owned it for three years. All I have done is new plugs, oil, starter bracket and fuel line. Never checked the points or pulled the heads.
Mike Thomas
Marine City, MI
77 ex Palm Beach
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| Re: [GMCnet] Onan, Backfire [message #163798 is a reply to message #163783] |
Wed, 21 March 2012 21:58 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Mike,
That may have been caused by carbon build up on the heads. Those buildups
can glow hot enough to ignite the remaining fuel mixture after the ignition
is shut off. It's a good idea to periodically (100 hours? -- I don't
remember) remove the cylinder heads and clean them, and the piston and
valve tops. You can usually re-use the gaskets, especially if you give
them a good coat, on each side, with aluminum spray paint -- reassemble
them wet. <1 hour job.
JWID if I still had an Onan,
Ken H.
On Wed, Mar 21, 2012 at 9:08 PM, Thomas Mike wrote:
>
>
> My Onan purrs like a kitten. The other day I shut it down and it
> backfired. Scared the you know what out of me. Today I started it up and it
> backfired during start up and then started and ran great.
>
> Any suggestion on what is going on or how do I fix?
>
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: Onan, Backfire [message #163803 is a reply to message #163783] |
Wed, 21 March 2012 22:38 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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| MikeT wrote on Wed, 21 March 2012 19:08 |
My 6K Onan purrs like a kitten. The other day I shut it down and it backfired. Scared the you know what out of me. Today I started it up and it backfired during start up and then started and ran great.
Any suggestion on what is going on or how do I fix?
Thanks
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Mine has done that off and on and I found that it was a poor connection between the remote harness at the generator end--a very common problem. What happens is that sometimes when shutting it down, the connection is marginal and it thinks you have released the stop switch and tries to continue running. It will do the same on startup since it momentarily thinks it needs to stop and then restarts. Almost all backfires are due to excess fuel in the combustion chamber and a spark when it didn't expect one. I would clean the connection were the wires from the contol board plug into the coach harness. That connector is always problematic.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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