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Onan BF Will Not Crank


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  #1  
Old 11-07-2017, 12:13:33 AM
signmakerdoc signmakerdoc is offline
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Default Onan BF Will Not Crank

BF will not crank when start button is depressed, but resistor, and relay have been replaced
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Old 11-07-2017, 12:48:26 AM
nothingbutdarts nothingbutdarts is offline
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Default Re: BF Onan will not crank

Any more history on the set? Why were the resistor and relay replaced? Can you hear a relay click when you hit the start switch?
When you hold in the start switch are you getting voltage to the coil+ and fuel pump?
Is the starter solenoid new?
You should Please post the full model and serial number.
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Old 11-07-2017, 04:58:00 AM
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Default Re: BF Onan will not crank

Quote:
Originally Posted by signmakerdoc View Post
BF will not crank when start button is depressed, but resistor, and relay have been replaced
"...resistor, and relay have been replaced"

For what reason?
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Old 11-07-2017, 06:29:59 AM
JohnnyC JohnnyC is offline
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Default Re: BF Onan will not crank

Ah, did you replace the relay with an over the counter Ford relay from the autoparts store?

JohnnyC
New Jersey
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Old 11-07-2017, 02:54:55 PM
signmakerdoc signmakerdoc is offline
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Default Re: BF Onan will not crank

the unit is BF-3CR/16000B And No, it is not a generic relay, it purchased from Generator Specialists in North Lima, Oh. The resistor was changed because there was No resistance
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Old 11-07-2017, 03:28:12 PM
nothingbutdarts nothingbutdarts is offline
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Default Re: BF Onan will not crank

History of the set, something that just happened? Has it been running fine till now?
Do you hear a click when you push the start button?
When you say relay, you are talking about the little cube relay correct?
The starter solenoid is original?
I believe there are at least 1 fuse in the front panel or maybe two, have you checked those?
The resistor you replaced, is it the charge resistor in the back generator section?
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Old 11-07-2017, 03:46:28 PM
signmakerdoc signmakerdoc is offline
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Default Re: BF Onan will not crank

yes, the one in the control box, original solenoid, and yes the charge resistor, and still trying to Get running, removed heads to remove carbon, new head gaskets, torqued 16-18 lbs, new plugs, new oil pressure switch
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Old 11-07-2017, 03:46:40 PM
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Default Re: BF Onan will not crank

POLLUTION just like craigs list Lst your post several times BECAUSE YOU ARE SPECIAL
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Old 11-07-2017, 03:54:45 PM
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Default Re: BF Onan will not crank

Did it run before?

Do you hear clicking when you push start switch?

Fuses?

When you hold start switch, Do you hear clicking??????

Also when you hold start switch are you getting voltage to coil + ??????

Take a minute and answer these if you could.
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Old 11-07-2017, 04:05:12 PM
signmakerdoc signmakerdoc is offline
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Default Re: BF Onan will not crank

Been working on it from time to time sine I purchased it over a year ago. In one of my earliest posts, I had the problem of it starting, running for a couple minutes, then shutting down, so the replacement of these parts was an effort to correct the earlier problem
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Old 11-07-2017, 04:20:32 PM
nothingbutdarts nothingbutdarts is offline
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Default Re: BF Onan will not crank

OK so this is a post on this unit then.

https://www.smokstak.com/forum/showthread.php?t=159500

So again, could you answer ALL the questions in my last post????
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Old 11-07-2017, 04:44:39 PM
signmakerdoc signmakerdoc is offline
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Default Re: BF Onan will not crank

Serial #B773 235450

Yes, this IS my post

When I got this genset, it hadn't run in abut 5 or 6 years, came out of an rv, Paid $50. fuses are goo, there is 12v to the coil
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Old 11-07-2017, 05:16:07 PM
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Default Re: BF Onan will not crank

Any chance you could post a picture of the inside of the control box????
I can't remember how many terminals there are on the start solenoid inside the control box.
If you have a GOOD set of jumper cables, can you jump one end of the start solenoid on the big 5/16" lug to the other big lug and see if the engine will try to turn over? It draws a lot of amps. to turn the engine over!!!
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Old 11-07-2017, 05:22:12 PM
JT240Z JT240Z is offline
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Default Re: BF Onan will not crank

Quote:
Originally Posted by signmakerdoc View Post
Been working on it from time to time sine I purchased it over a year ago. In one of my earliest posts, I had the problem of it starting, running for a couple minutes, then shutting down, so the replacement of these parts was an effort to correct the earlier problem
So, if you could start it in the past, I would look at something you've done since then.
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Old 11-13-2017, 11:14:46 AM
signmakerdoc signmakerdoc is offline
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Default Re: BF Onan will not crank

Found another problem, I wanted to make sure everything in the control wiring was good, so I connected the battery, and it started smoking out of the control box, so I took it off, the only melted wires were to the relay, replaced the wires. So was wondering if it was a matter of a short, so I laid the cover on a piece of plastic, hooked up the battery, no short, no fried wires??????????????????????????????????
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Old 11-13-2017, 09:29:34 PM
Imaybail Imaybail is offline
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Default Re: BF Onan will not crank

The control box needs to be grounded for the starter relay to work. The relay is just a standard Bosch type relay. Onan relay is four poles labeled 1,2,3 & 4. These correspond to 85, 30, 86, & 87 on the Bosch relay.
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Old 11-14-2017, 10:22:49 AM
signmakerdoc signmakerdoc is offline
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Default Re: BF Onan will not crank

I believe I may have found the problem, upon further investigation I found the spacer grommet for the rectifier was bad, so I just put the rectifier in a shrink tube, put the control back in place, no more short, now on to further testing. Thank you again for the help
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Old 11-14-2017, 03:34:33 PM
signmakerdoc signmakerdoc is offline
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Default Re: BF Onan will not crank

can someone tell me the proper spark plug to be using in this genset
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Old 11-14-2017, 03:49:17 PM
JT240Z JT240Z is offline
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Default Re: BF Onan will not crank

Quote:
Originally Posted by signmakerdoc View Post
can someone tell me the proper spark plug to be using in this genset
Champion old # H8C New # CHA 587 according to the manual. Pray tell, may I ask what that would have to do with the beast not cranking?

Last edited by JT240Z; 11-14-2017 at 04:04:01 PM.
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Old 11-15-2017, 01:08:44 PM
signmakerdoc signmakerdoc is offline
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Default Re: BF Onan will not crank

Cranking problem has been resolved, tuning it up before I do any further testing, unit had not been used for at least 5 years, came out of an early 70's RV
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