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Onan Generators

Onan 7.5 JB-3CR31/9286T


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  #11  
Old 08-04-2015, 05:11:32 PM
Max Thompson Max Thompson is offline
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Default Re: Onan 7.5 jb-3cr31/9286t

The price is not bad if it is in good condition.

The trouble with buying a J series it that you will lose interest in the RV sets after you play with the JB for awhile.

Build sheet attached.
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  #12  
Old 08-07-2015, 07:47:39 PM
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Onan Dan Onan Dan is offline
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Default Re: Onan 7.5 jb-3cr31/9286t

well if the good lord wills and the creek does not rise my son in law and myself is heading for or close to Lake Erie tomorrow to take a look at this 7.5JB I got the regulators and tool box and every thing needed loaded to check it out Leon sure has helped me out here telling me what to check and so on he knows these JB,S like the back of his hand I sure hope it is a runner
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  #13  
Old 08-07-2015, 11:12:08 PM
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Default Re: Onan 7.5 jb-3cr31/9286t

Dan, I just aquired a tri fuel JB and they are nice units. Yours might have the HIGH compression pistons for vapor fuel only. That will get you full output with natural gas. Mine, even though it is an extended stack generator end will only give me 6.7KW on natural gas. Mine has the 6.5 to 1 pistons. The one you are looking at might have the 9 to 1 pistons. More efficient on cu ft of gas per hour than mine will be. Good luck on your find my friend! Chris
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Old 08-08-2015, 07:06:25 AM
MBB MBB is offline
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Default Re: Onan 7.5 jb-3cr31/9286t

Dan here is some additional info on your unit your picking up today.
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Old 08-08-2015, 07:12:29 AM
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Default Re: Onan 7.5 jb-3cr31/9286t

Dan here is some additional info on your unit your picking up today.
Wiring Diagram not the best but readable. OOps double post.
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Old 08-08-2015, 08:03:02 AM
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Default Re: Onan 7.5 jb-3cr31/9286t

Thanks fellows a fire station had this JB so hopefully it is in good condition it will be along trip for me son in law doing the driving have a nice day

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Dan here is some additional info on your unit your picking up today.
Wiring Diagram not the best but readable. OOps double post.
Hi Mike the attached files I open them and both are just black pages nothing there unless my ole pc is acting up? thx
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  #17  
Old 08-08-2015, 08:24:48 AM
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Billy J Shafer Billy J Shafer is online now
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Default Re: Onan 7.5 jb-3cr31/9286t

Try again Dan. I just opened all three.Well two pages on one and a single page on the other.
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Old 08-09-2015, 11:19:58 AM
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Default Re: Onan 7.5 jb-3cr31/9286t

Made the road trip turned out to an 8 hour trip stop once for Gasoline and then on the way back stop for dinner . The JB all checked out and then I started it started right up and set there and ran smooth the t2 was grounded in control box and the magneciter is a pretty tan color we blew out a lot mice nest first and the oil has been keep changed here it turns out this JB was used in city of Erie for a radio tower got the single phase 60 amps trans fer switch and he also gave me a three phase transfer switch probably will not be able to use either one this Jb and the switches are all new to me the pictures does not due these onans justice 475 pounds and it is huge the transfer switches weigh a lot. so I am well pleased for the price 550 thanks to all for the info .
the oil pressure a few minutes after running was 45 pounds and the meter showed 123 volts holding steady.
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Old 08-09-2015, 12:07:05 PM
Leon N. Leon N. is offline
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Default Re: Onan 7.5 jb-3cr31/9286t

Dan, sounds like you did very well, better than I did back in 1970. I paid $500 for my JB and had to refurbish it. Your readings are very good. Next week I will prepare that Onan color 22 page brochure for you. Not sure, but since your JB was designed for natural gas, you may have the high compression version, meaning you should get the full 32 amps@ 240 volts ( that is the name plate rating of 7500 watts) very easily. With a little TLC, this machine will remain very reliable.
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Old 08-09-2015, 01:04:38 PM
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Default Re: Onan 7.5 jb-3cr31/9286t

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Originally Posted by Onan Dan View Post
Thanks fellows a fire station had this JB so hopefully it is in good condition it will be along trip for me son in law doing the driving have a nice day



Hi Mike the attached files I open them and both are just black pages nothing there unless my ole pc is acting up? thx
Dan if you still have problem let me know I will send them to your email.

Nice job on your new acquisitions. The road trips are half the fun.
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