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Onan 6.5 NHE starts but won't stay running.


I have an Onan 6.5 Emerald III Genset (6.5NHEFA26100D options A223 & Z497). It starts but will not...

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Old 08-19-2009, 12:58 AM
dalewall dalewall is offline
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Default Onan 6.5 NHE starts but won't stay running.

I have an Onan 6.5 Emerald III Genset (6.5NHEFA26100D options A223 & Z497). It starts but will not run, in the past, cleaning the carb has solved this problem. This time it is not generating AC current and thus shuts off spark to the plugs as soon as I let off the starter switch.

I found a troubleshooting guide (www.flightsystems.com/pdf/onanrvtshootgd608.pdf) which led me to discover that the slip rings were very dirty and I have cleaned them up, now getting 22 or 23 ohms between pins 9 & 10 on the regulator plug.

I do not get voltage between B1 and B2 pins 1 & 7 at the control board.

I do get 10-12 VDC at the FIELD FLASH pin (5) of the control board during
cranking.

I was not able to get it to stay running with External Excitation (apply 12 volts through a diode to pin 9 of the regulator plug).

I have the installation, parts, and operator's manuals, but I may need a service manual.

I will buy a new control board or regulator if needed but would like to know I am actually ordering the part I need.

My friend says he can likely fix the board if I could find a schematic, he is very good with electronics.

Any help would be appreciated.
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Old 08-19-2009, 03:16 AM
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Default Onan 6.5 NHE starts but won't stay running.

Here is a typical NHE wiring diagram.
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File Type: pdf Emerald.pdf (135.5 KB, 472 views)
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Old 08-19-2009, 08:25 AM
dalewall dalewall is offline
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Default Re: Onan 6.5 NHE starts but won't stay running.

Bruce,

Thanks, I read your reply and went out to the unit and printed on it is "wiring diagram part no. 611-1180". I'm guessing this is similar but slightly varied from the 611-1174 you posted.

I cranked this over so many times while trying to figure it out, at one point the 5A slow blow fuse failed and I replaced it. I am also amazed with how dirty the slip rings were that it was still generating power last winter when I used it.
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Old 08-19-2009, 12:01 PM
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Talking Re: Onan 6.5 NHE starts but won't stay running.

One of the things "I" do to ALL my Gensets is to replace the Fuses with Circuit Breakers. Seems like the fuse will ALWAYS blow at the most inconvenient time, when the wind is ripping, the rain is going sideways, and Momma is cold and asking where are the lights. Then you can never find a replacement, in the dark, with a flashlight with dead batteries. should be able to find these in Port A. or forks at a Marine Electric Shop. Certainly in Seattle, or Bremerton.
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Old 08-19-2009, 01:23 PM
dalewall dalewall is offline
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Default Re: Onan 6.5 NHE starts but won't stay running.

A breaker sounds like a great idea for the future, but at present I'm in need of a working generator. I'm trying to determine what B1 and B2 refer to.
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Old 08-19-2009, 07:48 PM
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Talking Re: Onan 6.5 NHE starts but won't stay running.

B1 and B2 are the Genend winding connections that feed the Bridge Rectifier that powers the Engine Control System, and the Battery Charging Circuit.
If you don't get power across B1 & B2, the Engine DIES, when you release the Start Switch.
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Old 08-19-2009, 09:05 PM
George Clark George Clark is offline
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Default Re: Onan 6.5 NHE starts but won't stay running.

looks like you need to clean your brushes and slip rings, send me an email and i will send you the service manual please include your model number,georgenfw@hotmail.com
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Old 08-22-2009, 01:16 PM
dalewall dalewall is offline
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Default Re: Onan 6.5 NHE starts but won't stay running.

So now I have a new voltage regulator from flight systems and it says the gas motor needs to run at a steady RPM without surging.

If the generator isn't producing AC, the control board shuts down the gas motor. How do I get the gas motor to run so I can make sure it is running smooth before install the new regulator?
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Old 08-22-2009, 01:45 PM
pegasuspinto pegasuspinto is offline
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Default Re: Onan 6.5 NHE starts but won't stay running.

that is just part of the troubleshooting so you hopefully won't call them and say "my voltage and Hz are all over the place, your regulator is junk". just install it and go on . if a little surging is gonna ruin it, it aint worth the box it came in.

Robert
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Old 08-23-2009, 12:09 AM
dalewall dalewall is offline
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Default Re: Onan 6.5 NHE starts but won't stay running.

The regulator works, the gen set is running and producing AC power. It surges for a bit after startup until I turn the air conditioner on. The load seems to make it run much smoother.
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Old 08-23-2009, 12:27 AM
Dave Edmonds Dave Edmonds is offline
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Default Re: Onan 6.5 NHE starts but won't stay running.

Tweaking of carb adjustments may fix the no-load surging problem. It did for the NH I'm in the process of mounting on a trailer. Once I got mine to run with a new control board, solenoid, carb cleanup, fuel pump "unistick" and battery, I adjusted idle jet and gave it a 4 KW load for about 3 hours. Initially did fine, but once it warmed up (gets REAL warm when working for a living), it began to surge. Adjustment of the high-speed jet fixed that. The board I got was from Flight Systems - fisrt-class workmanship, nice people to deal with.
Dave Edmonds
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Old 08-24-2009, 02:10 AM
dalewall dalewall is offline
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Default Re: Onan 6.5 NHE starts but won't stay running.

This 6.5 runs two roof A/C units and other appliances at a normal temp. That little flat head is a tough motor, I 'd love to have something quieter though, even when you reduce the exhaust noise there is quite a bit of mechanical noise from the moving engine parts.
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