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Onan 4GBE spark problem


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  #1  
Old 03-05-2017, 12:53:27 AM
bbqjoe bbqjoe is offline
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Default Onan 4GBE spark problem

I found a few threads here that came real close to the same exact problem, but unfortunately, sometimes people get so excited when their problem is solved, they forget to post what fixed it.

Anyway, I'm sorry if I missed a solution. Onan generator. Model# 4BGEFAZ6100P. Sat for 10 years. Ran when put away.
Mice got to the wiring.
I went through the wiring harnesses and repaired each wire one by one so as not to mix anything up.

I found some burnt and lifted traces on the control board.
No telling why, but quite possibly due to some shorts from the mice.
Went ahead and replaced the board, the fuel pump, filters, oil etc.


This is out of an RV, and has been stand alone forever.

The engine cranks, maybe not getting fuel to the carb, but that's beside the point for right now, I think.
I pulled the plug and did a spark test.

The start switch is new with the board, and comes mounted on it.
The switch is a two or three way rocker, depending on how you see it.
One direction is start, after start it rests in the middle, until rocked the other direction to stop.

There is no spark when cranking, until I let off the start switch, then I see a couple of sparks as the engine quits spinning.

Argh!!!

I very vaguely remember putting a jumper in the remote start coupler for some reason, although I'm not 100% on that, I wasn't very sober back in those days.

Any ideas, work arounds or things I might try?

Thanks,


Joe
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  #2  
Old 03-05-2017, 08:51:52 AM
Kevin K Kevin K is offline
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Default Re: Onan 4GBE spark problem

The mice probably got into the generator end, made a nest, and when the engine was cranked the plastic ignition rotor hit the nest and snapped. This is a common cause of a no spark condition in the Emerald series.

Go here to download the manuals:
http://www.twinslan.net/~n0nas/manuals/onan/

965-0528 service
965-0231 Parts
965-0176 Operator
965-0628 Install

Page 6-10 of the service manual describes the procedure for troubleshooting a no spark condition.
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Old 03-05-2017, 10:24:01 AM
Pete Spaco Pete Spaco is offline
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Default Re: Onan 4GBE spark problem

Small point about your model number, but I think the "Z" is a "2". And the complete serial number might help to get the age and spec, which could be important for determining which wiring diagram is for your set.

I don't know for sure about the 4BGE, but the 6.5NHE had points up to and including spec D. I think later spec models had that electronic ignition stuff.

Pete Stanaitis
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Old 03-05-2017, 11:42:33 AM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

Quote:
Originally Posted by Kevin K View Post
The mice probably got into the generator end, made a nest, and when the engine was cranked the plastic ignition rotor hit the nest and snapped. This is a common cause of a no spark condition in the Emerald series.

Go here to download the manuals:
http://www.twinslan.net/~n0nas/manuals/onan/

965-0528 service
965-0231 Parts
965-0176 Operator
965-0628 Install

Page 6-10 of the service manual describes the procedure for troubleshooting a no spark condition.
Thank you for your reply.
The serial # is F990 936 408

I did read about the plastic rotor, but let me ask, if the rotor got snapped off, why would I be getting some spark?

I'm going to go look at the manual, thanks for the link.

---------- Post added at 10:42:33 AM ---------- Previous post was at 10:36:38 AM ----------

Holy banoonies. I went to look for the manual.
Sorry, I'm lost.
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  #5  
Old 03-05-2017, 01:04:24 PM
len k len k is offline
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Default Re: Onan 4GBE spark problem

Your gen is spec P, and has electric ignition, with the plastic rotor.

Since it sat for 10 years, first thing to do is disconnect the AC voltage reg VR1. Otherwise if engine starts the dirty slip rings will very likely stress the ~$200 voltage reg and kill it. By disconnecting reg , if engine starts it will stop when you release start button, but you will have protected the $$$ reg. Can then clean slip rings with scotchbrite pad and reconnect the reg.

To test ignition system put a 12V test light across the spark coil primary terminals( low voltage ones), crank engine. Light should blink steadily while cranking if plastic rotor arms are intact and ignition modual is good.

If the plastic rotor is snapped off I believe you get ONE spark when you press the start button and ONE spark when you release it . none in between. Might get same results if it's ignition modual that detects the arm magnet is bad. If you have this pattern of spark pull the ignition modual and looks down the hole to see if plastic rotor arms have broke off. Look at service manual page 6-10

Last edited by len k; 03-05-2017 at 01:22:35 PM.
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Old 03-05-2017, 01:34:02 PM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

I just put a test light on low volt terminals and cranked.
Light comes on steady. No blink.
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Old 03-05-2017, 01:45:32 PM
len k len k is offline
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Default Re: Onan 4GBE spark problem

If your test light was ACROSS the coil terminals, then pull the ignition modual and look down the hole to see if the plastic rotor arms have broke off.
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Old 03-05-2017, 03:06:40 PM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

Module pulled. Rotor presence verified, magnet present on end of arm.

---------- Post added at 02:02:08 PM ---------- Previous post was at 02:00:59 PM ----------

Oh wait, is there more than one arm?

---------- Post added at 02:06:40 PM ---------- Previous post was at 02:02:08 PM ----------

Nuts. Looked closer. Supposed to be 2 arms huh? One is gone.
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Old 03-05-2017, 03:09:36 PM
len k len k is offline
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Default Re: Onan 4GBE spark problem

Plastic rotor has 2 arms. Magnet at end of each arm.

Look at item #5 on paper page 25, in parts manual 965-0231.
Rotor is part # 166–0842 ...... Rotor Assembly, Ignition (Includes Rotor and Magnet)

Last edited by len k; 03-05-2017 at 03:23:13 PM.
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Old 03-05-2017, 04:26:14 PM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

Thanks Len. I'm so not looking forward to splitting this thing. But it doesn't look too hard.
Pull carb, and maybe 4 bolts?
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Old 03-05-2017, 06:47:33 PM
Tony Clever Tony Clever is offline
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Default Re: Onan 4GBE spark problem

Service Manual:
http://www.twinslan.net/~n0nas/manua...0(09-1994).pdf

Parts Manual:
http://www.twinslan.net/~n0nas/manua...0(01-1998).pdf

Operators Manual:
http://www.twinslan.net/~n0nas/manua...0(07-1997).pdf

Installation Manual:
http://www.twinslan.net/~n0nas/manua...0(10-1996).pdf

Hope this helps

RE: Holy banoonies. I went to look for the manual.
Sorry, I'm lost.

Last edited by Tony Clever; 03-05-2017 at 07:00:26 PM.
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Old 03-05-2017, 10:42:51 PM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

I just had a thought.
It looks like an awful lot of trouble to split the engine from the generator.

Is there any reason at all that I can't mount the ignition sensor above the cooling fan on the rear, and mount magnets to the fan so they correspond to TDC?
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Old 03-05-2017, 10:50:47 PM
len k len k is offline
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Default Re: Onan 4GBE spark problem

Actually I was thinking of something like that for my other Onan. I think most of these emeralds have a power take off mount on end of genhead,
I was thinking of drilling the flywheel and press fitting magnets into it. But that may be a hot area, electronics don't like high temps.
Likley will require trial and error. Installed into ferrous metal ( steel) the magnetic field at the sensor may be distorted by the steel. May require playing with gap and timing ( degs before TDC)

You can trial and error it but, If you use the gen's ignition modual likely would be a good idea to position the magnets at least about same radius from spin axis as on rotor. Has to do with how fussy you have to position the modal, smaller radius might be harder to adjust, but you can try it.
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Old 03-05-2017, 10:59:17 PM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

I'm going to give it a shot.
They should have placed them somewhere like that in the first place.

I recently started working on small 200 cc honda engines.
They mount the magnets right on the metal flywheel without detriment to the signal.
There might be a little adjusting here and there, but I still have one arm attached.
I can put that in a position I can see at TDC, and get pretty close in line where the first magnet should go, then just go 180º and mount the other.

I'm of the opinion they make this so difficult, you just buy a new generator.

If it works, great! If not, it can sit another ten years and not be missed.
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Old 03-05-2017, 11:27:38 PM
len k len k is offline
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Default Re: Onan 4GBE spark problem

I see no reason magnets can't be installed in steel flywheel, just may have to play with gap and maybe angular position to get the timing advance you want.
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Old 03-05-2017, 11:40:05 PM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

On a small engine, the gap is about a credit cards width, sometimes up to .040.

There's some pretty crazy adhesives out there as well.
One might just drill a hole in the magnets, and another on the flywheel or fan or what ever it's called, then tap for a screw.
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Old 03-06-2017, 08:01:07 AM
Kevin K Kevin K is offline
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Default Re: Onan 4GBE spark problem

If you try this, and you intend to use the original Onan pickup, just be aware of the polarity of the magnets. On the plastic arm, the magnet on one arm is North, the magnet on the other arm is South. One turns the current to the coil on, the other turns the current off and produces the spark. The Onan electronic ignition system is different from most other systems.

On the other hand, if you use another electronic ignition such as the GM HEI system, you need only one magnet to trigger the spark.

The timing on the electronic ignition BGE generators is 14 to 18 degrees BTC.

You might want to consider cleaning the mouse nest and broken plastic arm out of the generator end before it gets caught in the starter gear.
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  #18  
Old 03-06-2017, 10:44:01 AM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

This is most curious. I have never heard of a south magnet vs a north magnet.
Every magnet I've ever dealt with had a south pole and a north pole.
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Old 03-06-2017, 11:04:21 AM
Kevin K Kevin K is offline
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Default Re: Onan 4GBE spark problem

Same thing. Every magnet has both a north and south pole. On the Onan arm, one arm has the south pole on the tip, the other arm has the north pole on the tip.
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Old 03-06-2017, 11:15:11 AM
bbqjoe bbqjoe is offline
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Default Re: Onan 4GBE spark problem

I'm sure I will experiment with this concept.
Somehow I doubt an unconnected entity such as the sensor knows a south polarity passing by it vs a north passing by.

I don't know a whole lot about these things, but I remember we studied magnets one day in science class when I was about ten.
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