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Onan 7.5 JB Fuel Efficiency


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  #11  
Old 04-13-2018, 02:10:14 PM
Leon N. Leon N. is offline
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Default Re: Onan 7.5 JB Fuel Efficiency

What do you mean by: "take full load in one step"? The JB recovery spec from NL to full rated load is 2 seconds, meaning recovering to within 5% on frequency and 3% on voltage.
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  #12  
Old 04-13-2018, 03:11:26 PM
consolenut consolenut is offline
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Default Re: Onan 7.5 JB Fuel Efficiency

I noticed that if too lean the generator will labor or stumble a bit when a decent load kicks in. If that is the case i add about a 1/4 turn to the carb to richen it up. I aim for a smooth transaction between no load and say a 20 amp hit. You will hear it a little but it wont seem like the genset is being pulled to its knees.


As Leon stated. If the carb is set fairly close the generator will stabilize voltage wise very very quickly. I've watched the LCD meters for voltage and frequency and the rapid rate of recovery and stability is neat to see. I haven't seen any other brand genset recover so fast if at all.
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Old 04-13-2018, 03:28:58 PM
Leon N. Leon N. is offline
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Default Re: Onan 7.5 JB Fuel Efficiency

As I maintain, they do not build them like that anymore. Just look at the Onan specifications above under the Vintage Literature. Not bad considering this came out of the 1960's era.
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Old 04-13-2018, 03:49:47 PM
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Motorhead Motorhead is offline
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Default Re: Onan 7.5 JB Fuel Efficiency

If your set was vapor only from new, the timing from the factory should be set at the more advanced setting.
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Old 04-13-2018, 04:00:55 PM
Vanman Vanman is offline
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Default Re: Onan 7.5 JB Fuel Efficiency

"Full load in one step" means going from no load to full rated load in one step.

Here is a 6-1/2 kw Kohler taking well more than full load in one step. The load is a 5,000 watt tungsten lamp which, when cold, is much lower resistance than when at operating temperature.

Notice that the throttle goes wide open almost instantly, yet there is no hesitation. Then you see the throttle back off as the lamp comes up to temperature.

https://m.youtube.com/watch?v=7-pcwto-ofI

Last edited by Vanman; 04-13-2018 at 04:29:48 PM.
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