Generators and Motors
[Home] - [HELP] - [Forums] - [Library] - [Photo Gallery] - [Groups] - [Classified Ads] - [Subscribe] - [Links] - [Books] - [Sponsors] -

Go Back   SmokStak > SmokStak® Vintage Electrical Equipment > Generators & Motors General Discussion > Onan Generators
Forgot Password? Join Us!

Notices

Onan Generators Restoring, operating and maintaining vintage Onan generators.

Onan Generators

Onan 4.0kW Generator has been sitting for at least 6 years


this thread has 32 replies and has been viewed 1155 times

Reply
 
Thread Tools Display Modes
  #1  
Old 04-14-2017, 05:53:34 PM
twitchee2 twitchee2 is offline
Registered
 
Join Date: Apr 2017
Location: Camarillo, California
Posts: 12
Thanks: 4
Thanked 0 Times in 0 Posts
Default Onan 4.0kW Generator has been sitting for at least 6 years

Hi guys, I have been doing quite a bit of reading on this forum trying to find the answer I and so far I have been striking out. First off, I apologize, I do not have my serial number for the generator right now. I will try to get it soon. Here is what I do know. It is an Emerald 1 Genset, I know it is a 4.0BGE Gas powered unit.

This is in a 1986 Winnebago that I recently picked up and this is one of things that is not working properly. I am a back yard gear head and I almost have the Ford 460 running right. Rebuilt card, new vac lines, all new ignition, full tune up etc.

I have narrowed it down to not getting fuel. The fuel pump was jammed up from not being used in a very long time. I unscrewed the bottom and free'd the plunger up. I can hook up a car battery to it directly and it pumps fuel just fine from the tank. I still will likely replace it, but it works well enough to get this thing operational.

I manually pumped fuel to the carb with the battery. If I hit the start switch and it will fire up and run until it runs out of fuel 5-10s, maybe. But after connecting everything back together, the fuel pump is not running. I am an engineer at an electronics manufacturer so I brought the old PCB in and had my failure analysis manager take a look at it. There is nothing obvious and all the components work properly.

I have studied the schematics for this unit as best I could but am not sure where to go from here. Where does this PCB get the signal to enable the fuel pump?

Thanks!
Reply With Quote
Sponsored Links
  #2  
Old 04-14-2017, 06:16:03 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 13,828
Thanks: 350
Thanked 4,995 Times in 3,632 Posts
Default Re: Onan 4.0kW generator has been sitting for atleast 6 years

Need the full model and serial numbers.

But in general on the control board the same relay that powers the spark coil also sends power to the pump. But on some boards they put in a series diode with outputs. All diodes can easily blow if you short their output to ground.

Trace the wire from pump back to the board and see if you have power out of the board.
Reply With Quote
The Following User Says Thank You to len k For This Post:
  #3  
Old 04-14-2017, 06:32:00 PM
twitchee2 twitchee2 is offline
Registered
 
Join Date: Apr 2017
Location: Camarillo, California
Posts: 12
Thanks: 4
Thanked 0 Times in 0 Posts
Default Re: Onan 4.0kW generator has been sitting for atleast 6 years

Quote:
Originally Posted by len k View Post
Need the full model and serial numbers.

But in general on the control board the same relay that powers the spark coil also sends power to the pump. But on some boards they put in a series diode with outputs. All diodes can easily blow if you short their output to ground.

Trace the wire from pump back to the board and see if you have power out of the board.
Will do that again. I actually did that and saw some funky voltage, almost an AC voltage. What should I expect? Solid ~13v voltage, Correct?
Reply With Quote
  #4  
Old 04-14-2017, 06:47:14 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 13,828
Thanks: 350
Thanked 4,995 Times in 3,632 Posts
Default Re: Onan 4.0kW generator has been sitting for atleast 6 years

Voltage to pump or spark coil should be something like 10VDC to bat voltage.

If it's jumping around erratically it could be a bad connection, burnt relay contact, or just spark coil loading the line down as coil charges between firings.
Reply With Quote
  #5  
Old 04-14-2017, 08:30:32 PM
Motorhead's Avatar
Motorhead Motorhead is offline
Subscriber
 
Join Date: May 2007
Location: Central Coast, California
Posts: 3,130
Thanks: 1,344
Thanked 1,961 Times in 1,081 Posts
Default Re: Onan 4.0kW generator has been sitting for atleast 6 years

I would suggest cleaning the GENERATOR slip rings BEFORE trying to get power out of it or running it for any length of time. I learned this from len k. This saves the voltage regulator from dying a quick death.
__________________
Back of 1958 5CCK
Contractors model
On trailer owned by
"Ma" Bell.
Reply With Quote
The Following User Says Thank You to Motorhead For This Post:
  #6  
Old 04-14-2017, 09:04:10 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 13,828
Thanks: 350
Thanked 4,995 Times in 3,632 Posts
Default Re: Onan 4.0kW generator has been sitting for atleast 6 years

Yes, if it's spec D or higher it has a $$$ electronic AC votlage reg that can die if gen sits for months and you don't clean slip rings before running.

10-15 seconds at no load is about the time it takes mine empty the carb bowl too , if pump is not reloading it with gas.

Last edited by len k; 04-14-2017 at 10:49:25 PM.
Reply With Quote
  #7  
Old 04-15-2017, 12:04:30 AM
twitchee2 twitchee2 is offline
Registered
 
Join Date: Apr 2017
Location: Camarillo, California
Posts: 12
Thanks: 4
Thanked 0 Times in 0 Posts
Default Re: Onan 4.0kW generator has been sitting for atleast 6 years

So I am very new when it comes to generators, is there a write up on how to get to the slip rings? I swung the generator down from the mounts, do I just take the cover off and clean the rings with some rubbing alcohol?

When I said I work for a electronics manufacturer, I should say we are a motion control company, I am very familiar with the inner workings on electric motors, etc.

Thanks!
Reply With Quote
  #8  
Old 04-15-2017, 02:00:15 AM
Motorhead's Avatar
Motorhead Motorhead is offline
Subscriber
 
Join Date: May 2007
Location: Central Coast, California
Posts: 3,130
Thanks: 1,344
Thanked 1,961 Times in 1,081 Posts
Default Re: Onan 4.0kW generator has been sitting for atleast 6 years

Take a piece of Scotchbrite and clean the slip rings. you can remove the spark plugs so it turns easy and fit an Allen wrench in the hex at the generator end to turn the generator rotor. I remove the brush block on my BGE to get better access but make sure the screws aren't seized in the threads and you break off the hold down screws. DON'T leave the generator hanging at a steep angle for a day or more. The crankcase oil can fill a cylinder and lock the engine.
__________________
Back of 1958 5CCK
Contractors model
On trailer owned by
"Ma" Bell.
Reply With Quote
The Following 2 Users Say Thank You to Motorhead For This Post:
  #9  
Old 04-15-2017, 12:32:33 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 13,828
Thanks: 350
Thanked 4,995 Times in 3,632 Posts
Default Re: Onan 4.0kW generator has been sitting for atleast 6 years

Scotchbrite, no rubbing alcohol or liquids.

To clean mine I , made a tool from a kitchen fork. I ground off the side tines of a 4 tine fork, tied a strip of scotch brite to it, and held it under the slip rings. Didn't have to remove brush holder. I'm lazy so I let engine run, but I unplugged AC reg first to protect it. But my gen is a NHM, so it will run while not making AC. You'll have to crank engine, removing the spark plugs will be easier on the starter. I wouldn't crank it for more than 10 sec without letting starter cool ~ a minute.
Reply With Quote
  #10  
Old 04-15-2017, 01:30:31 PM
Power Power is offline
Registered-III
 
Join Date: Aug 2011
Location: New Jersey
Posts: 3,869
Thanks: 910
Thanked 2,202 Times in 1,294 Posts
Default Re: Onan 4.0kW generator has been sitting for atleast 6 years

I use a popsicle stick with scotchbrite taped to end.
If something goes wrong, and pad gets caught, stick will break with minimal damage to gen, and none to my hand.

No way am I holding a piece of metal near supposedly dead slip rings, or a commutator .
also, if metal get caught, may do damage to gen.
Reply With Quote
The Following User Says Thank You to Power For This Post:
  #11  
Old 04-15-2017, 03:50:27 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 13,828
Thanks: 350
Thanked 4,995 Times in 3,632 Posts
Default Re: Onan 4.0kW generator has been sitting for atleast 6 years

I've used my fork method under slip rings several times on my NHM, it's pretty much identical to BGE design. The curve of fork tines fits slip rings very well. When placed under slip rings, the rings rotate away from you, so seems no risk of getting caught. Just don't let go. At that small diameter the surface velocities seem minimal to me, but I'm a ME and everyone has to make that judgment call for themselves

I however have did this with AC voltage reg unplugged so there is no voltage in genhead. Well actually real reason reg was unplugged is because it's still in cellar still waiting for me to remove more of it's potting and repair it.
Reply With Quote
  #12  
Old 04-16-2017, 12:14:01 PM
twitchee2 twitchee2 is offline
Registered
 
Join Date: Apr 2017
Location: Camarillo, California
Posts: 12
Thanks: 4
Thanked 0 Times in 0 Posts
Default Re: Onan 4.0kW Generator has been sitting for at least 6 years

Thanks for all the suggestions guys. I didn't get a chance to really play with it yesterday and doesn't look like I will be getting a chance until tomorrow or the next day. I did look to see and I think I will need to completely drop it out of the RV.

Anyway, here is the full model number and spec


Also, here is the signal to the Fuel pump. It looks like some sort of PWM signal that is ~60V, that doesn't seem correct does it?
Reply With Quote
  #13  
Old 04-16-2017, 12:24:05 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 13,828
Thanks: 350
Thanked 4,995 Times in 3,632 Posts
Default Re: Onan 4.0kW Generator has been sitting for at least 6 years

The control board won't make PWM , it's just simple relays and maybe a series diode. The PWM pattern has to be coming from either inductive kick back from the solinoid in the gas pump or from inductive kickback from the spark coil. Try unplugging the pump ( at the pump) and see if PWM pattern is still there.

Can't read the voltage scale on the voltage/time graph. What's the voltage at the bottom of the spikes? I'm guessing it's bat voltage ~ 13VDC. Right??

Also what's the voltage at the peaks of the spikes?

-----------------------

Your gen is spec C (version number).
Manual numbers and link to them:

BGE-BGEL spec a-c SERVICE--(5-89)--- 965-0530.pdf <---------------------read this one
BGE (A-E)---BGEL (B-D) --PARTS---965-0232 Emerald I.pdf
BGE-BGEL--INSTALL---965-0630.pdf
BGE-BGEL OPERATOR---965-0130.pdf

http://www.twinslan.net/~n0nas/manuals/onan/

Last edited by len k; 04-16-2017 at 12:43:13 PM.
Reply With Quote
The Following 2 Users Say Thank You to len k For This Post:
  #14  
Old 04-16-2017, 12:43:15 PM
pegasuspinto pegasuspinto is offline
Registered-III
 
Join Date: Oct 2006
Location: Floyd, AR, USA
Posts: 2,486
Thanks: 317
Thanked 1,144 Times in 752 Posts
Default Re: Onan 4.0kW Generator has been sitting for at least 6 years

I bet you are the first one to hook an expensive 'scope to the fuel pump power lead. So no frame of reference to know if what you see is a normal by-product of how the set works...
Reply With Quote
The Following User Says Thank You to pegasuspinto For This Post:
  #15  
Old 04-16-2017, 01:04:37 PM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 13,828
Thanks: 350
Thanked 4,995 Times in 3,632 Posts
Default Re: Onan 4.0kW Generator has been sitting for at least 6 years

Never know what's there till you look at it.
The old simple relay logic and points didn't care about spikes , no electronic to kill.

Kickback is likely why newer model gens (NHM) have a zener diode from +12V spark coil lead to ground.
And a freewheeling diode across relay that powers the Onan 7NHM pump.
NHM is very similar to BGE, but control board is design a bit differently.

Interestingly on Chevys I see freewheeling diodes across motors and solinoids to stop the inductive kick. Seen them on A/C electro cluch on pump, relays and other places..... helps protect the computer from damaging spikes.
Reply With Quote
  #16  
Old 04-16-2017, 08:06:55 PM
twitchee2 twitchee2 is offline
Registered
 
Join Date: Apr 2017
Location: Camarillo, California
Posts: 12
Thanks: 4
Thanked 0 Times in 0 Posts
Default Re: Onan 4.0kW Generator has been sitting for at least 6 years

The bottom of the those spikes is ~10V which makes sense. the scale is 20V/div so spike to about 100V. Time scale is 200ms/div so I bet those spikes are is noise from each spark. That first picture is at the fuel pump power lead with the pump disconnected.

This picture below is with the Pump connected. it is sitting very close to 10V which is more normal. I think it is safe to say the PCB is working properly.


That you for all of those manuals! I have some reading to do and likely some cleaning to do on the slip rings, etc.
Reply With Quote
  #17  
Old 04-17-2017, 12:13:35 AM
twitchee2 twitchee2 is offline
Registered
 
Join Date: Apr 2017
Location: Camarillo, California
Posts: 12
Thanks: 4
Thanked 0 Times in 0 Posts
Default Re: Onan 4.0kW Generator has been sitting for at least 6 years

I haven't had a chance to take check the brushes and clean the slip rings yet. Assuming those get cleaned and brushes are all good. What do I need to check next. I would assume clean the carb, but am I missing anything else?

Thanks for all your help so far!
Reply With Quote
  #18  
Old 04-17-2017, 12:38:28 AM
Motorhead's Avatar
Motorhead Motorhead is offline
Subscriber
 
Join Date: May 2007
Location: Central Coast, California
Posts: 3,130
Thanks: 1,344
Thanked 1,961 Times in 1,081 Posts
Default Re: Onan 4.0kW Generator has been sitting for at least 6 years

Pull the points cover and clean and check the point gap. Any idea of the total hours on the generator? If it has 1000 hrs or more, I would suggest you adjust the valves. If the oil in the set has sludge at the bottom of the oil pan then I would change the oil and filter, run the set with a good load for an hour or so then change the oil and filter again and put your favorite "flavor" of engine oil and a GOOD oil filter. I run Rotella T6 full synthetic, 5/40 diesel rated oil. It still has the good stuff in it for flat tappet cams and it sticks to parts well.

I feel the 4BGE and that series of small sets were some of the last decent sets made by Onan before they went to the 3600 RPM, 1 quart oil capacity, no oil filter sets. My $0.02 worth.
__________________
Back of 1958 5CCK
Contractors model
On trailer owned by
"Ma" Bell.
Reply With Quote
  #19  
Old 04-17-2017, 01:10:23 AM
twitchee2 twitchee2 is offline
Registered
 
Join Date: Apr 2017
Location: Camarillo, California
Posts: 12
Thanks: 4
Thanked 0 Times in 0 Posts
Default Re: Onan 4.0kW Generator has been sitting for at least 6 years

Quote:
Originally Posted by Motorhead View Post
Pull the points cover and clean and check the point gap. Any idea of the total hours on the generator? If it has 1000 hrs or more, I would suggest you adjust the valves. If the oil in the set has sludge at the bottom of the oil pan then I would change the oil and filter, run the set with a good load for an hour or so then change the oil and filter again and put your favorite "flavor" of engine oil and a GOOD oil filter. I run Rotella T6 full synthetic, 5/40 diesel rated oil. It still has the good stuff in it for flat tappet cams and it sticks to parts well.

I feel the 4BGE and that series of small sets were some of the last decent sets made by Onan before they went to the 3600 RPM, 1 quart oil capacity, no oil filter sets. My $0.02 worth.
Already have some T6 to put in there with the extended filter. Per the hour meter its got 132hrs. Good call on the points.

Thanks!
Reply With Quote
  #20  
Old 04-20-2017, 12:48:09 AM
twitchee2 twitchee2 is offline
Registered
 
Join Date: Apr 2017
Location: Camarillo, California
Posts: 12
Thanks: 4
Thanked 0 Times in 0 Posts
Default Re: Onan 4.0kW Generator has been sitting for at least 6 years

Cleaned the Slip rings, they certainly needed to be cleaned up a bit. All good there. Tried to fire it up and nothing. It would run on starting fluid. Doubled checked the fuel pump and it is pumping just fine!

Pulled the carb off and Huston we have a problem! Nothing in the carb moved freely, it was so gummed up and nasty. Got it all nice and clean, just need to get a couple of O-rings and think she's going to be running just fine!

I will update in a couple of days!

Real quick, once I get it fired up how do I check the voltages and frequency? Are there any regulators I need to worry about?
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

F o r u m Jump

Similar Threads Chosen at Random
Thread Thread Starter F o r u m Replies Last Post
Onan 4.0BF-3CR/16000B RV Generator Startup After Sitting for 6 Years farmer52 Onan Generators 26 10-21-2015 11:50:52 AM
1911 FBM 4 hp T after sitting many years Mark S Frank Antique Gas Engine Discussion 5 11-22-2013 10:26:20 PM
Onan 20ES Starting after Sitting for 10 years Curtis 916 Onan Generators 15 11-23-2012 02:44:36 AM
onan engine sitting for years lafhouse Onan Generators 14 09-09-2011 07:50:47 AM
Sitting 50+ years the Gilson runs Brian.P Antique Gas Engine Discussion 17 02-10-2008 07:51:29 AM


Use "Ctrl" mouse wheel to change screen size.
All times are GMT -4. The time now is 11:00:26 AM.

Smokstak and Enginads site search!


All use is subject to our TERMS OF SERVICE
SMOKSTAK® is a Registered Trade Mark - A Community of Antique Engine Enthusiasts
Copyright © 2000 - 2016 by Harry Matthews P.O. Box 5612 - Sarasota, FL 34277