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Onan Emerald NHE Idle Problem


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  #41  
Old 03-05-2017, 07:49:12 PM
Ed III Ed III is offline
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Default Re: Onan Emerald NHE Idle Problem

The generator is now working normally. Thanks to all who provided help here !! This project started as a simple repair and went to a "not going to let it whip me challenge." I am going to provide information from beginning to end, just in case there is someone who might be helped by the information. I may have some out of chronological order, but essentially correct.

In the beginning, the unit was dead. Upon checking, the starter solenoid was found to be the culprit and it was replaced. The unit then would start, but run no longer than the start button was held down. That indicated no generator output to feed itself after the switch disconnected the battery. Resistance was checked at the brushes and found to be high. Brushes and slip rings were cleaned. Resistance returned to factory spec, but did not correct the problem. The control board checked good, but the generator still had no output. The regulator was checked for opens/shorts and was found to be bad. New regulator installed and unit started running..........but it was surging and running badly. Did a tune up with plugs, points and condenser. No change. Cleaned carb several times and finally got the engine running properly (thanks Len). Setup was performed according to the manual using my multitester which has a cycles position (thanks Kevin)

Nice to have it working. I am sure I have more in it than it is worth. It sneaked up on me a little at a time. Regulator was over $200, carb kit was $70, solenoid was $45, tune up parts $75 or so, oil change $18, $38 for a carb jet and I built a cart for it !! A lot, but I will get my money out of it. 😇

Thanks so much for your assistance.

Ed
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  #42  
Old 03-05-2017, 09:51:20 PM
Dale Russell Dale Russell is offline
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Default Re: Onan Emerald NHE Idle Problem

Atta Boy Ed, on "Not letting it get the best of you", NEVER GIVE UP!, even when you can't see the light at the end of the tunnel. Glad you conquered it! Give's you that good feeling doesn't it?
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  #43  
Old 03-06-2017, 08:30:17 AM
Kevin K Kevin K is offline
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Default Re: Onan Emerald NHE Idle Problem

Quote:
Originally Posted by Ed III View Post
I am sure I have more in it than it is worth. It sneaked up on me a little at a time.
Truer words were never spoken!
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  #44  
Old 03-06-2017, 10:05:07 AM
Max Thompson Max Thompson is offline
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Default Re: Onan Emerald NHE Idle Problem

Quote:
Originally Posted by Ed III View Post
I am sure I have more in it than it is worth. It sneaked up on me a little at a time.
Go try to buy one comparable to it and you will find you Do Not have too much in it.

Plus, you have the confidence and experience to fix it the next time.
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Old 03-06-2017, 10:13:40 AM
Ben Cowan Ben Cowan is offline
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Default Re: Onan Emerald NHE Idle Problem

Motörhead beat me to it. Paper lips are great for keeping brushes compressed against springs while reassembling. Sometimes I experiment and cut to different lengths. Start by straightening out paper clips. Then measure length of wire needed. I usually cut them about 3/4 of an inch too long so extra sticks out and can be pulled out after block is in place and screws are almost snug. I use needle nose pliers to grab paper clip pieces to remove them. Next I snug brush screws test each brush for free movement finish tightening screws. Luck, Ben
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  #46  
Old 03-06-2017, 11:01:21 AM
Ed III Ed III is offline
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Default Re: Onan Emerald NHE Idle Problem

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Originally Posted by Max Thompson View Post
Go try to buy one comparable to it and you will find you Do Not have too much in it.

Plus, you have the confidence and experience to fix it the next time.
The only thing I felt ripped off about was the carb kit. It lacked almost everything I really needed. Those gaskets can be easily made for a buck or so. The jets aren't included. I basically paid $70 for the intake needle (as I call it) that the float operates. The rest of the kit was things that mostly don't wear out. If one looks closely, the exploded diagrams of the carb put out by Onan do not show the idle jet assembly. Somewhere it said, "do not rebuild carburetor, replace it."

Ed
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  #47  
Old 03-09-2017, 06:14:16 PM
Ed III Ed III is offline
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Default Re: Onan Emerald NHE Idle Problem

I think I should post this information about surging/hunting. I read this information somewhere, perhaps here, but did not fully comprehend it. On this style generator, where the governor rod connects to the carburetor, there is a clip. The clip has the ability to apply a very slight resistance to the governor rod movement. While you don't want much resistance, a little is needed. If you take a pair of pliers and press the two circles close to each other, this will add the needed amount of friction and can prevent "minimal" surging. A picture is attached.

This seems too simple, but it works in some cases. Hopefully the photograph will eliminate any confusion.

Ed
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  #48  
Old 04-14-2017, 03:28:43 PM
Ed III Ed III is offline
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Default Re: Onan Emerald NHE Idle Problem

The generator seems to have been doing quite well. I do want to run this by the group to see if there is a problem here. Since this involves the voltage regular, which is expensive, I don't want to take any chances.

When I start the system, if I release the start button sooner than 8 or 10 seconds, it cuts off. I recall with the old voltage regulator, I could release the start button as soon as the unit started and it continued running. I contacted Flight Systems and they say I have a problem with the brushes. I checked the resistance at the brushes and it is 25.3 ohms, which is right in the middle of the acceptable range.

Soooooo, is this something I ignore and hold the button a few seconds, or do I have a problem that needs to be resolved?? I would hate to pay over $200 for a regulator and find out after the warranty period that it was defective from the start.

Thanks,

Ed
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  #49  
Old 04-15-2017, 08:36:50 PM
Pete Spaco Pete Spaco is offline
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Default Re: Onan Emerald NHE Idle Problem

I think I'd want to see WHY it quits. If the spark goes away, that's one kind of problem. If the sparks keep coming, could be choke too lean, for instance.

I've said this before, but I think anyone who works on spark ignition engines should have one of these in their pocket at all times:
Dorman - Conduct-Tite Electrical Tester - In-Line Spark Plug Checker
(There are cheaper ones available from China, I think)

If sparks go away:
You may have to do a better job of cleaning the slip rings. They can look clean and they can ohm out okay when at rest, but if there's ANY bounce to them or any oxidation anywhere, the effective resistance can change once the engine is turning.

I hate to admit it here, but I have a 6.5NHE that starts better if I connect a couple hundred watt load to it when I crank it, after it sits for a while.

Pete Stanaitis
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  #50  
Old 04-15-2017, 10:39:22 PM
Ed III Ed III is offline
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Default Re: Onan Emerald NHE Idle Problem

Thanks for the reply. I haven't done any tests, but I am 99% certain that it quits because when the switch is released, excitation voltage quits and the control board is not yet getting the voltage from the generator necessary to keep the ignition coil energized.

Perhaps I should install a new set of brushes and clean the slip rings again. I was under the impression that the correct ohm reading was the deciding factor, but I can now see how the brushes could bounce.

Ed
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  #51  
Old 04-18-2017, 09:11:24 PM
Ed III Ed III is offline
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Default Re: Onan Emerald NHE Idle Problem

Pete, thanks, you were right about the brushes/slip rings. I can see now that one needs to check the resistance in several different positions to get a true reading. There were a few dark areas on my slip rings, but the resistance would check good MOST of the time. I originally cleaned the rings and sanded the rings, but I did not have a polished finish. It wasn't good enough.

As a side issue, I saw a test of the brushes using a wire with paint on one inch. When placed into the brush holder, one should be able to see paint outside the holder. The test confirmed my brushes are good. I used coat hanger wire.

Today, after polishing the rings for about an hour, I have a nice shiny finish all the way around. The resistance was consistent on multiple tests. When started this time, I released the button, almost immediately and it kept running. I understand this sort of problem kills (very expensive) voltage regulators. Glad I didn't ignore the warning.

Ed
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  #52  
Old 04-18-2017, 11:03:48 PM
len k len k is offline
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Default Re: Onan Emerald NHE Idle Problem

When I cleaned , let gen sit 3-5 months, then measured resistance rotating fly wheel every 5 deg, I found severral high resistance spots . Seems the copper/brass rings corrode under the carbon brushes, galvantic corrosion maybe.
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  #53  
Old 04-23-2017, 11:47:44 AM
Jim Marcozzi Jim Marcozzi is offline
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Default Re: Onan Emerald NHE Idle Problem

When doing carbs on single RPM devices such as generators, pressure washers and hydraulic pumps, I close the idle off completely by either seating the needle or even using epoxy if I'm inside of the carb doing a repair. The main jet can handle all of the fuel without the idle. Remember- the idle jet just allows fuel to bypass the closed throttle valve. Anywhere above, it's simply not needed. At 1800RPM, the main jet can do all of the work just fine, as you're not throttling down even at low loads. And let's not forget that these engines' governors go to W.O.T. when not running. You're also starting them at W.O.T. Done it many times and never once had any issue. The idle really IS irrelevant on a generator that runs at one speed.
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  #54  
Old 04-23-2017, 12:10:54 PM
len k len k is offline
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Default Re: Onan Emerald NHE Idle Problem

Theoretically during full load dump the carb goes to ~ closed throttle till engine slows. Idle jet might help keep engine from stalling during that time. I never tried it.
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