Home » Public Forums » GMCnet » What is it now? Generator issue.
| What is it now? Generator issue. [message #317412] |
Thu, 11 May 2017 22:06  |
kwharland
Messages: 246
Registered: November 2005
Location: Central Florida
Karma: 0
|
Senior Member |
|
|
Fired the genset up this afternoon. It started easily after priming and ran smoothly for 20-30 minutes. I had turned both A/C's on while it was running and right before it quit, it sounded like it was running out of gas.
I know it's not a good thing to shut down a generator under load and I think it has damaged itself now that it did so.
I turned off the A/C's, tried to re-start the generator and it took several tries, firing and dying immediately then finally starting and running smoothly. I gave it 5 to 10 minutes then went to turn the A/C's back on and neither came on. The generator sounds like it has a load applied but nothing is happening with A/C units.
What died now?
1978 Eleganza II
|
|
|
|
|
|
| Re: What is it now? Generator issue. [message #317414 is a reply to message #317413] |
Thu, 11 May 2017 22:19  |
Hal StClair
Messages: 971
Registered: March 2013
Location: Rio Rancho NM
Karma: -12
|
Senior Member |
|
|
Check the 120 volt breakers.
Hal
"I enjoy talking to you. Your mind appeals to me. It resembles my own mind, except you happen to be insane."
1977 Royale 101348,
1977 Royale 101586, Diesel powered,
1974 Eagle Bus 45',w/slideout,
Rio Rancho, NM
|
|
|
|
|
|
| Re: What is it now? Generator issue. [message #317427 is a reply to message #317413] |
Fri, 12 May 2017 07:25 |
kwharland
Messages: 246
Registered: November 2005
Location: Central Florida
Karma: 0
|
Senior Member |
|
|
A Hamilto wrote on Thu, 11 May 2017 23:16kwharland wrote on Thu, 11 May 2017 22:06Fired the genset up this afternoon. It started easily after priming and ran smoothly for 20-30 minutes. I had turned both A/C's on while it was running and right before it quit, it sounded like it was running out of gas.
I know it's not a good thing to shut down a generator under load and I think it has damaged itself now that it did so.
I turned off the A/C's, tried to re-start the generator and it took several tries, firing and dying immediately then finally starting and running smoothly. I gave it 5 to 10 minutes then went to turn the A/C's back on and neither came on. The generator sounds like it has a load applied but nothing is happening with A/C units.
What died now? Check the bridge rectifier.
That's on the genset, right?
1978 Eleganza II
|
|
|
|
| Re: What is it now? Generator issue. [message #317428 is a reply to message #317412] |
Fri, 12 May 2017 07:42 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
|
Senior Member |
|
|
Regarding the first problem, Examine /replace every inch of fuel line feeding the generator. Mine had an almost invisible split where it was clamped to the fuel pump barb sucking air. Regarding no AC output, flip or push breaker on top of Onan itself. If no 120V get a meter and meter the line side of breaker. If still no, the bridge rectifier may have failed under the plastic air intake grill. This is more envolved if you are electrcally challenged.
John Lebetski
Woodstock, IL
77 Eleganza II
|
|
|
|
|
|
|
|
| Re: What is it now? Generator issue. [message #317454 is a reply to message #317428] |
Fri, 12 May 2017 13:07 |
kwharland
Messages: 246
Registered: November 2005
Location: Central Florida
Karma: 0
|
Senior Member |
|
|
JohnL455 wrote on Fri, 12 May 2017 08:42Regarding the first problem, Examine /replace every inch of fuel line feeding the generator. Mine had an almost invisible split where it was clamped to the fuel pump barb sucking air. Regarding no AC output, flip or push breaker on top of Onan itself. If no 120V get a meter and meter the line side of breaker. If still no, the bridge rectifier may have failed under the plastic air intake grill. This is more envolved if you are electrcally challenged.
Thanks John, everything on the fuel system has been gone through recently, I'll find why it stopped after I diagnose the electrical issue. I was drawing a blank of the bridge rectifier which is why I posted.
1978 Eleganza II
|
|
|
|
|
|
| Re: What is it now? Generator issue. [message #345061 is a reply to message #317412] |
Tue, 09 July 2019 15:53 |
kwharland
Messages: 246
Registered: November 2005
Location: Central Florida
Karma: 0
|
Senior Member |
|
|
Well, I'm finally back on it and still facing the same issue - no power. I almost started a new thread but then all that courteously responded to this one would start all over and I'd have to answer all the same questions again.
Here's the backstory - two years ago generator was running fine, both A/C's on and cooling and I stepped away for a bit and came back to find generator had stopped. Turned off A/C's and restarted, now no power coming out. Since it died with a load, suspected bridge rectifier had failed. Then life got in the way and this problem went unaddressed since then. I've started and run the engine and driven it periodically during that time but that's all I had time to do. And fortunately it still starts and runs fine.
So back to the generator and the rectifier - as I went to pull it out, I saw a wire off the lower brush housing. Wasn't sure if I pulled it off accidently but pushing it back on was way too easy so it either fell off on its own and which would be my good luck, or I bumped and it came off. Tightened the quick disconnect and pushed it back on, started the generator but still no power. Oh well, one can hope!
So I finished pulling the rectifier, tested it and found all diodes open, or so I thought. Bought a new one and just out of curiosity, tested it as well and got the same results!! WTH! Changed the DVM to the 20k scale and diodes measure 9k ohms in one direction and open in the other. Checked the old rectifier - same results! Turns out cheap DVMs don't put out enough voltage on the lower scales to pass current through a diode!
So anyway, back to my problem. I decided to check the condition of the lower set of brushes and found one with the wire misrouted and keeping it from fully extending. I corrected that and with fingers crossed, re-installed and restarted the generator. Nope - no joy!
I spent some time reading all other 'Onan with no power' threads and it appears the only thing I haven't tried is flashing the thing. What I'm unsure about it how do I determine F1 and F2? In all the reading I've done today, I haven't spotted the answer. I do read 38 ohms across the windings so I'm not dealing with a short or open.
Something to keep in mind, it was 2 years ago when I started this thread. The generator at that time had not been run in some time (months) as I was chasing a control board problem. I replaced the control board with one of the new Dino models and was running it when it died and then lost power. Now it's been sitting for two years but still starts and runs smoothly.
So should I flash it?
Another question though, does the control board play any role in this power generation. I would think it does and that's the one thing that was changed before this occurred with a new dino board. Could I be looking at some issue related with changing the board?
1978 Eleganza II
|
|
|
|
| Re: [GMCnet] What is it now? Generator issue. [message #345064 is a reply to message #345061] |
Tue, 09 July 2019 16:58 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
|
Senior Member |
|
|
The control board has nothing to do with the charging only with motor starting and running and low oil pressure shutoff.
If your bridge rectifier tests all right then you could try flashing the magnetic field.
Check all connectors on the generator. There are some in plastic tubes by the brushes. The spade connectors are brass and they loose their tension and provide poor connections. I replaced mine with steel ones years ago and covered them with electrolytic grease to prevent corrosion. That took care of my charging problems.
Emery
> On Jul 9, 2019, at 2:53 PM, Ken Harland via Gmclist wrote:
>
> Well, I'm finally back on it and still facing the same issue - no power. I almost started a new thread but then all that courteously responded to
> this one would start all over and I'd have to answer all the same questions again.
>
> Here's the backstory - two years ago generator was running fine, both A/C's on and cooling and I stepped away for a bit and came back to find
> generator had stopped. Turned off A/C's and restarted, now no power coming out. Since it died with a load, suspected bridge rectifier had failed.
> Then life got in the way and this problem went unaddressed since then. I've started and run the engine and driven it periodically during that time
> but that's all I had time to do. And fortunately it still starts and runs fine.
>
> So back to the generator and the rectifier - as I went to pull it out, I saw a wire off the lower brush housing. Wasn't sure if I pulled it off
> accidently but pushing it back on was way too easy so it either fell off on its own and which would be my good luck, or I bumped and it came off.
> Tightened the quick disconnect and pushed it back on, started the generator but still no power. Oh well, one can hope!
>
> So I finished pulling the rectifier, tested it and found all diodes open, or so I thought. Bought a new one and just out of curiosity, tested it as
> well and got the same results!! WTH! Changed the DVM to the 20k scale and diodes measure 9k ohms in one direction and open in the other. Checked the
> old rectifier - same results! Turns out cheap DVMs don't put out enough voltage on the lower scales to pass current through a diode!
>
> So anyway, back to my problem. I decided to check the condition of the lower set of brushes and found one with the wire misrouted and keeping it from
> fully extending. I corrected that and with fingers crossed, re-installed and restarted the generator. Nope - no joy!
>
> I spent some time reading all other 'Onan with no power' threads and it appears the only thing I haven't tried is flashing the thing. What I'm unsure
> about it how do I determine F1 and F2? In all the reading I've done today, I haven't spotted the answer. I do read 38 ohms across the windings so
> I'm not dealing with a short or open.
>
> Something to keep in mind, it was 2 years ago when I started this thread. The generator at that time had not been run in some time (months) as I was
> chasing a control board problem. I replaced the control board with one of the new Dino models and was running it when it died and then lost power.
> Now it's been sitting for two years but still starts and runs smoothly.
>
> So should I flash it?
>
> Another question though, does the control board play any role in this power generation. I would think it does and that's the one thing that was
> changed before this occurred with a new dino board. Could I be looking at some issue related with changing the board?
> --
> 1978 Eleganza II
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
|
|
|
|
| Re: [GMCnet] What is it now? Generator issue. [message #345067 is a reply to message #345061] |
Tue, 09 July 2019 17:56 |
Jim Miller
Messages: 501
Registered: March 2008
Karma: 10
|
Senior Member |
|
|
> On Jul 9, 2019, at 4:53 PM, Ken Harland via Gmclist wrote:
> I spent some time reading all other 'Onan with no power' threads and it appears the only thing I haven't tried is flashing the thing. What I'm unsure
> about it how do I determine F1 and F2? In all the reading I've done today, I haven't spotted the answer. I do read 38 ohms across the windings so
> I'm not dealing with a short or open.
Flash the field using a 12V battery.
How to identify? F1 is attached to the bridge + terminal and F2 to bridge - terminal. See pp. 44 of the 6kW service manual for the schematic that shows this.
Disconnect F1 and F2 from the bridge before flashing.
Use only a battery for this procedure... do not use a DC power supply because the flyback voltage pulse from the field windings can cook your power supply.
Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
|
|
|
|
| Re: [GMCnet] What is it now? Generator issue. [message #345073 is a reply to message #345067] |
Tue, 09 July 2019 20:41 |
 |
ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
|
Senior Member |
|
|
Did you actually replace the bridge rectifier? That’s my first suspect.
The loose wire I had assumed was for the early starter battery charging before the house batteries did the trick.
I am frequently besotted with overthinking issues and under acting on them!
Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont California
On Jul 9, 2019, at 3:56 PM, Jim Miller via Gmclist wrote:
>> On Jul 9, 2019, at 4:53 PM, Ken Harland via Gmclist wrote:
>
>> I spent some time reading all other 'Onan with no power' threads and it appears the only thing I haven't tried is flashing the thing. What I'm unsure
>> about it how do I determine F1 and F2? In all the reading I've done today, I haven't spotted the answer. I do read 38 ohms across the windings so
>> I'm not dealing with a short or open.
>
>
> Flash the field using a 12V battery.
>
> How to identify? F1 is attached to the bridge + terminal and F2 to bridge - terminal. See pp. 44 of the 6kW service manual for the schematic that shows this.
>
> Disconnect F1 and F2 from the bridge before flashing.
>
> Use only a battery for this procedure... do not use a DC power supply because the flyback voltage pulse from the field windings can cook your power supply.
>
>
> Jim Miller
> 1977 Eleganza
> 1977 Royale
> Hamilton, OH
>
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
|
|
|
|
| Re: What is it now? Generator issue. [message #345081 is a reply to message #317412] |
Wed, 10 July 2019 10:24 |
kwharland
Messages: 246
Registered: November 2005
Location: Central Florida
Karma: 0
|
Senior Member |
|
|
Thanks for the responses, all are appreciated.
First thing I did today was pull the old rectifier and flash the magnetic field with a 12 volt battery. I actually closed the connection to the battery 3 - 4 times, leaving it connected for 2-3 seconds each time. Does it take more than that?
Installed old rectifier - no power
Modified new rectifier to fit connector housing and installed it- no power.
What I did notice but may have not been looking for before was as soon as the starter disengaged, there was 3 - 6 VAC briefly at the breaker. In earlier tests I was not holding the test lead to the breaker until after the engine was running. Today I held it there as I started the motor so what I saw may have always been the case, whatever that means.
I have not pulled the upper brushes but have looked closely at the connections and they appear to be well attached. I can see why changing out those brushes would be a pain! Based on the amount of brush remaining on the lower ones, and assuming all are the same age, the uppers should be fine. There is approximately the same length of the braided wire loop from the brush to its connector in the uppers as is in the lowers.
What next?
1978 Eleganza II
|
|
|
|
| Re: What is it now? Generator issue. [message #345082 is a reply to message #317412] |
Wed, 10 July 2019 10:45 |
kwharland
Messages: 246
Registered: November 2005
Location: Central Florida
Karma: 0
|
Senior Member |
|
|
I disconnected the wires to the lower brushes and there is continuity between them, so they're not open.
And assuming the armature is grounded through its bearing and into the housing, there isn't a short within the armature.
At this point,the generator should be putting out AC power! The only component not tested or replaced is the compounding reactor but it doesn't seem to be related to a 'no power' condition.
1978 Eleganza II
|
|
|
|
| Re: What is it now? Generator issue. [message #345084 is a reply to message #345082] |
Wed, 10 July 2019 11:22 |
mghamms
Messages: 466
Registered: March 2016
Location: Ware, Massachusetts
Karma: 2
|
Senior Member |
|
|
Low ac voltage and high fluctuating hertz is more than luckily a problem with the bridge rectifier.
I noticed that the original is marked for ac but not + and -.
Try rotating ithe new one 180 degeres.
1977 Kingsley 455 as stock as it gets except lots of Ragusa parts
[Updated on: Wed, 10 July 2019 11:23] Report message to a moderator |
|
|
|
| Re: [GMCnet] What is it now? Generator issue. [message #345085 is a reply to message #345081] |
Wed, 10 July 2019 11:41 |
Emery Stora
Messages: 959
Registered: January 2011
Karma: 4
|
Senior Member |
|
|
Did you check for voltage at both sides of the circuit breaker at the top of the Onan?
I worked on a friend’s Onan once that had 120 volts at both sides so I knew that the Onan was generating power. I found that the wire leading to the plug in the electrical compartment had an open. There was a connection at the wall where the wire from the Onan led inside the wall. The wire was broken there.
Emery Stora
> On Jul 10, 2019, at 9:24 AM, Ken Harland via Gmclist wrote:
>
> Thanks for the responses, all are appreciated.
>
> First thing I did today was pull the old rectifier and flash the magnetic field with a 12 volt battery. I actually closed the connection to the
> battery 3 - 4 times, leaving it connected for 2-3 seconds each time. Does it take more than that?
>
> Installed old rectifier - no power
>
> Modified new rectifier to fit connector housing and installed it- no power.
>
> What I did notice but may have not been looking for before was as soon as the starter disengaged, there was 3 - 6 VAC briefly at the breaker. In
> earlier tests I was not holding the test lead to the breaker until after the engine was running. Today I held it there as I started the motor so what
> I saw may have always been the case, whatever that means.
>
> I have not pulled the upper brushes but have looked closely at the connections and they appear to be well attached. I can see why changing out those
> brushes would be a pain! Based on the amount of brush remaining on the lower ones, and assuming all are the same age, the uppers should be fine.
> There is approximately the same length of the braided wire loop from the brush to its connector in the uppers as is in the lowers.
>
> What next?
> --
> 1978 Eleganza II
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
|
|
|
|
|
|
| Re: [GMCnet] What is it now? Generator issue. [message #345088 is a reply to message #345085] |
Wed, 10 July 2019 12:12 |
kwharland
Messages: 246
Registered: November 2005
Location: Central Florida
Karma: 0
|
Senior Member |
|
|
mghamms wrote on Wed, 10 July 2019 12:22Low ac voltage and high fluctuating hertz is more than luckily a problem with the bridge rectifier.
I noticed that the original is marked for ac but not + and -.
Try rotating the new one 180 degrees.'
The original is marked 'AC' and '-' and the new one is marked 'AC' and '+' and they correspond with each other with the plus and minuses being diagonally opposite each other. I guess if there's no harm I can rotate it but I've been careful to remove and install either correctly. Of course working upside down often leads to disorientation which is why I took pictures with my phone then marked the housing accordingly.
Emery Stora wrote on Wed, 10 July 2019 12:41Did you check for voltage at both sides of the circuit breaker at the top of the Onan?
Emery Stora
Yes but it's easy to see which side is which.
1978 Eleganza II
|
|
|
|
Goto Forum:
Current Time: Fri Sep 20 11:34:04 CDT 2024
Total time taken to generate the page: 0.01588 seconds
|
GMCforum
Search
Help
Register
Login
Home
