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Onan Emerald NHE Idle Problem

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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.

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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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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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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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