HOME MAGAZINE FORUM RULES SPONSORS CONTACT
     
   
   
 
Go Back   CLASS RACER FORUM > Class Racer Tech > Support Tech

Reply
 
Thread Tools Display Modes
Old 10-06-2017, 10:20 AM   #1
tonym
Junior Member
 
Join Date: Oct 2017
Posts: 5
Default Onan 4000 ky no start

Don't know where to look next. This unit is about 10 yrs old total hours unknown. It has good fuel and flow ,spark and compression. Carb was gone through completely . New spark plug also. Does the control module tell the engine to start? It does appear to be a timing issues since it makes a "puffin" sound while cranking and cycling. If so can the problem be with the module? Thank you.
tonym is offline   Reply With Quote
Old 10-06-2017, 01:23 PM   #2
Hacksaw
Member
 
Join Date: Sep 2016
Posts: 366
Default Re: Onan 4000 ky no start

I once had similar trouble with my 4000. When I was away from my trailer it ran out of fuel. After that it would start and run only while on cranking mode. Put in a new board to fix it. I'm guessing it didn't like the high and low rpm surging as it starved for fuel and fryed something.
Hacksaw is offline   Reply With Quote
Old 10-06-2017, 01:31 PM   #3
tonym
Junior Member
 
Join Date: Oct 2017
Posts: 5
Default Re: Onan 4000 ky no start

Thanks, Hacksaw
Is there any way to check module?
tonym is offline   Reply With Quote
Old 10-06-2017, 01:52 PM   #4
Hacksaw
Member
 
Join Date: Sep 2016
Posts: 366
Default Re: Onan 4000 ky no start

I'm sure there is but looks tricky to me. I'd bet most trouble shooters swap out the board with a good one rather than go through it. Those Onan gens have several "fail safe" circuits that run through that board.
Hacksaw is offline   Reply With Quote
Old 10-06-2017, 02:05 PM   #5
Hacksaw
Member
 
Join Date: Sep 2016
Posts: 366
Default Re: Onan 4000 ky no start

Hey Tonym: Remembered switching boards on mine and no difference. Just dug out copy of receipt for the repair and turns out I was mistaken. My fix was the voltage regulator, not the board. $149.00 in 2008. Sorry to aide in your confusion.
Hacksaw is offline   Reply With Quote
Old 10-07-2017, 09:54 AM   #6
tonym
Junior Member
 
Join Date: Oct 2017
Posts: 5
Default Re: Onan 4000 ky no start

Thanks, Hacksaw Ill check it .
tonym is offline   Reply With Quote
Old 10-07-2017, 01:58 PM   #7
Rich Biebel
VIP Member
 
Rich Biebel's Avatar
 
Join Date: Jun 2007
Location: Northern New Jersey suburbs
Posts: 1,840
Default Re: Onan 4000 ky no start

Your problem sounds like one I have seen a couple times.

The timing is off and here is why....

The engines crankshaft is keyed to the generators rotor. The rotor is keyed to the blower wheel and the timing is triggered by that blower wheel.

Either the blower wheel moved or more likely the rotor moved on the crank.

All tapered shaft connections and the crank to rotor has a little pin to locate it. The blower wheel has a key slot and a very small key. Once it's all bolted together the taper holds it. A backfire probably happened and sheared the pin at the rotor to crank connection and it moved.

If you have good spark, fuel and good compression this is likely your problem.......It should at least try to fire with carb cleaner sprayed into carb throat cranking. If it pops back or does nothing and you confirmed the spark is good......the timing is off and one of the above 2 items moved....

Like I said I have seen it at least twice and I fix these machines for years and years.....

If it cranks and has spark, it should at least start and would shut right down if it had no AC output or a bad control board. Bad boards sometimes burn up and won't even crank.....
__________________
Rich Biebel
S/C 1479
Rich Biebel is offline   Reply With Quote
Old 10-08-2017, 12:22 PM   #8
tonym
Junior Member
 
Join Date: Oct 2017
Posts: 5
Default Re: Onan 4000 ky no start

Many thanks,Rich I think you are correct. It sounds like it is trying to fire on exhaust stroke.


Can you guide me to how to approach the repair? How much disassembling is required to inspect the components etc and what do I look for?


Do you still run at Island? Think I remember you when me and my son raced there.! I live over in Brodheadsville near Stroudsburg.


Thanks Again.
tonym is offline   Reply With Quote
Old 10-08-2017, 05:08 PM   #9
Rich Biebel
VIP Member
 
Rich Biebel's Avatar
 
Join Date: Jun 2007
Location: Northern New Jersey suburbs
Posts: 1,840
Default Re: Onan 4000 ky no start

It's pretty difficult to describe and is a lot to disassemble. The entire generator end has to come apart. A service manual might help but you'd be better off taking it to a professional, like me that is familiar with them. It's not a simple deal to take it all apart and know what you are looking for. I work for a generator service company in Dover, NJ. I do all the RV work so I know those machines very well. I don't race at Island and have not for years. What racing I do is usually in S/C at various races and tracks. Maybe there is an Onan repair place somewhere in your area. You could buy a service manual online but it's not real helpful for a repair like this. There really is no other way to check this other than disassembling it to verify the timing indexing is either good or bad. A new rotor may be needed if the pin broke as it is not repairable. Parts availability is a possible issue but should be available.
__________________
Rich Biebel
S/C 1479
Rich Biebel is offline   Reply With Quote
Old 10-09-2017, 10:34 AM   #10
tonym
Junior Member
 
Join Date: Oct 2017
Posts: 5
Default Re: Onan 4000 ky no start

Thanks again, Rich
The unit is out of trailer and in my pickup. If you do any work on the side I can drive it to your place and leave it. I suspect I am only an hour or so away.
Assuming that's the problem can you give me a rough estimate to fix it . I don't want to put a lot of money in it if its not worth it.
Thanks so much


Tony
tonym is offline   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

Forum Jump


All times are GMT -5. The time now is 06:45 AM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright © Class Racer.com. All Rights Reserved. Designated trademarks and brands are the property of their respective owners.Ad Management plugin by RedTyger