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Onan 6.5 NH Running Badly


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  #11  
Old 05-06-2015, 08:24:23 PM
David C David C is offline
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Default Re: Onan 6.5 NH Running Badly

It sounds like an ignition problem more than a fuel problem. I would take a spare condenser to the camp with you. I recently had a CCK that had been running for about 8 hours when it started acting up. It was running on N/G and adjusting the mixture did not help. I cleaned the points, which did not help, so I left the point box cover off while it was running and noticed that the points would randomly arc excessively when it acted up. Put in a NOS condenser in and the points arced less all of the time, plus it quit the random arcing. It saw another 8 hours of service with no more problems.

As others mention, I would hook a test light to the positive side of the coil to see if you losing power to the coil.

David C.
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  #12  
Old 05-06-2015, 08:35:36 PM
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Billy J Shafer Billy J Shafer is offline
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Default Re: Onan 6.5 NH Running Badly

Sounds like bad points.
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  #13  
Old 05-06-2015, 10:09:23 PM
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BigBlockChev BigBlockChev is offline
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Default Re: Onan 6.5 NH Running Badly

Since it does this on both gas and propane it pretty much can't be a fuel issue. Others have said crappy points, maybe plug wires arcing maybe a loose/poor connection in the ignition circuit somewhere, maybe a relay contact is iffy, maybe a wire is broken inside the insulation, wiggle them all to see if you can force it to happen. Tighten all screws on terminal blocks. My buddy replaced about 10 thermocouples on his boiler before calling me, I replaced it again but then noticed a loose crimp on a spade terminal Cheers Dan
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  #14  
Old 05-07-2015, 10:22:17 AM
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Onan Dan Onan Dan is offline
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Default Re: Onan 6.5 NH Running Badly

Viking 66 last year about this time my 6.5 NH started acting up like this I had it tuned up and running like a new one it had new plugs points and condenser for 5 days it had me pulling my hair out . Jack DD said it sounds like a bad condenser ? so I put the old condenser back in that goes to the points hit that start switch and it ran like a new one. never gave the new condenser any thought it had less than ten hours on it. OD
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Old 05-07-2015, 10:42:56 AM
RSCurtis RSCurtis is offline
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Default Re: Onan 6.5 NH Running Badly

I'm with Max, it has an ignition problem.
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Old 05-07-2015, 11:12:41 AM
Sir Thomas Sir Thomas is offline
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Default Re: Onan 6.5 NH Running Badly

To measure resistance in the primary circuit,
connect one ohmmeter lead to the positive (+)
terminal and the other to the negative (-) terminal
on the coil. The resistance should be between
3.87 and 4.73 ohms. A high resistance value indicates
an open circuit or poor connection inside
the coil, and the coil should be replaced.
To measure resistance in the secondary circuit,
connect the ohmmeter leads to the two high tension
terminals (see Figure 6-8). The resistance
measured should be between 12,600 and 15,400
ohms. A lower resistance value indicates a
shorted secondary winding. A high resistance
value indicates the coil has excessive internal
resistance or an open circuit. Replace coil if not
within specifications.
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  #17  
Old 05-07-2015, 12:36:51 PM
len k len k is online now
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Default Re: Onan 6.5 NH Running Badly

I agree on trying to die. Since it's doing same on gasoline and vapor fuel it's likely not a fuel issue, I say ignition problem.

Check for intermittent low voltage connections first, put a small 12V test light between coil + and engine frame, check to see it stays on steady while engine is trying to die. Then put it across coil and see if it changes brightness as engine tries to die.

Back in the day on cars first thing you do for a problem like this is replace points and condenser, they go bad. Were cheap to replace. With no points in modern cars easy to forget you have to do this periodically with old engines.

Last edited by len k; 05-07-2015 at 12:52:18 PM.
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Old 05-07-2015, 04:49:26 PM
Viking66 Viking66 is offline
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Default Re: Onan 6.5 NH Running Badly

Thanks all.

The points I have are fairly new, but I think I have a new set and a Condenser here in my Garage. I now think, since it was pointed out...lol that it is ignition since it is doing it on both fuels.

I will not be able to go to my Camp this weekend, so I will not have a report back until a week from tomorrow. I will let you all know what it was.

Thanks as always!
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Old 05-15-2015, 03:10:16 PM
Viking66 Viking66 is offline
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Default Re: Onan 6.5 NH Running Badly

The Winner is..........Condenser. :

That was the first thing I decided to change and got lucky. She purred just like she had been doing before

I truly appreciate all of the suggestions and advice.

As always, this place is Awesome!!!!
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  #20  
Old 05-15-2015, 06:06:01 PM
Max Thompson Max Thompson is offline
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Default Re: Onan 6.5 NH Running Badly

Thanks for letting us know what the outcome was.
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