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Re: [GMCnet] I give up. (Onan) [message #190017 is a reply to message #189982] Mon, 12 November 2012 15:45 Go to previous messageGo to previous message
A Hamilto is currently offline  A Hamilto   United States
Messages: 4508
Registered: April 2011
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Robin Hood wrote on Mon, 12 November 2012 12:08

I have new and arguably interesting results!
...
Using starter spray after the regapping, the Onan coughed a couple of times. I believe that means that I have spark on at least one cylinder! That means that as long as the plugs and wires themselves are good that I do not have an ignition problem! And like Forrest Gump said, "That's one less thing to worry about."


That is very good news. I guess it was too much to hope for that you would get that cough the first time you tried the ether. Did you tell the Onan to turn its head before you checked for hernia?

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I put the carb back on the Onan, and crossed my fingers. After cranking and cranking away, she started to cough and sputter and rattled to life! It wasn't steady and strong, and it may have been missing (it sounded a lot like one of those hit-and-miss engines from the State Fair exhibit) but she ran for about a minute.


Not perfect, but a big leap forward. Next time you will be able to get to this point in a couple of hours instead of weeks.


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So. Carb is good(sh) now too. Need at least a gasket between the carb and manifold. The manual shows a gasket that's inside... I didn't take the "seat" out, I don't think I totally disassembled the carb. If the Berryman's Chem-Dip ate it, I'm gonna need a rebuild kit I think.
When I removed the jumper wire 9-5, and engaged the start button, the pump DID NOT start, and I cou'dn't even get the engien to catch. Is that significant?


Yes.

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Like a bad board type thing?


Yes.

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So, we have established that the new fuel pump works after a fashion (is it really enough, I wonder?)


Since it was intended to run an automobile, almost certainly (unless it is defective, not likely since it is new).

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the cleaned up carb works after a fashion (I'm unsure how good a job I did rebuilding it, and it may need a few new gaskets), and the ignition system works after a fashion (it ran, roughly, for a minute). All the fundamentals are there: fuel, air, spark, and compression.
The fuel pump not running when the board isn't jumpered has me concerned. But at least now I know what the problems are NOT.
To do: Order a rebuild kit from JimK for the carb. Possibly order a new board (the fuel pump should run when the start button is pressed and keep running, yes?).


Yes.

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Make it run again and measure the AC voltgage to make sure THAT is working, since that's the whole point after all. Start taking parts off and cleaning and painting them once things start running like they're supposed to (I put the carb adjustment screws back in the way I found them, but they may be out of whack to start with).


I would say you are correct on all your suppositions. You can only improve performance with a carb kit (does it include the one between the carb and intake?) and a gasket between the carb and intake. The sputtering and such means a fuel/air mixture problem, which may be a leak where the carb bolts on (where the gasket is missing) or the screws need to be adjusted, or both. Not likely any spark problems, seems to me on these engines, if you have spark at all, you have spark on both plugs.
There is something wrong with your board if it runs when jumpered and does not run when not jumpered. OR you have no oil pressure, or the "smarts" that can tell when it is running are not smart anymore (the board uses the charging circuit to tell if the engine is running, and turns off the fuel pump if it doesn't detect that the engine is running).
If you can get help from someone that knows how to tweak the carb screws (and possibly the governor), you can learn what to listen for to get it singing. I understand when you get the voltage right, the frequency is correct as well, but I would prefer to see it on a frequency counter if it was mine.

Hey everybody! There's a new Onan expert in Jackson, MS!
 
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