HOME FORUM RULES CONTACT
     
   
   

Go Back   CLASS RACER FORUM > Class Racer Tech > Support Tech
Register Photo Gallery FAQ Community Calendar


Reply
 
Thread Tools Display Modes
Old 10-14-2024, 10:19 PM   #1
Ed McLawhorn Jr.
Member
 
Join Date: Nov 2008
Posts: 291
Likes: 3
Liked 18 Times in 16 Posts
Default Onan 12.5kw issues

Need help on issues with 12.5kw diesel onan on my toterhome. Purchased toterhome in 2022 and no issues other than running rich (black smoke). Installed vent stack and gen would randomly cut off once or twice a weekend. No issues starting back and runing remainder of weekend. I didnt install stack and left storage door open for a couple races and no issues with cutting off. Recently, it has gotten worse and now cuts off 5-6 times during the weekend regardless of stack installed or storage door opened. This past weekend it was cutting off every couple hours. Most times, this weekend once it cut off, it would only start back after 20-30 minutes. Found code 45 and checked brushes today and they seemed clean. Only issue was one was much shorter than the other....seemed odd. Ordered new replacement brushes, but not confident brushes are the issue. Code 45 also indicates problem could also be pcb board. Assuming worst case, is it possible to change board without going to a onan repair dealer? Has anyone else had experience with code 45? Thanks for any suggestions.

Ed
Ed McLawhorn Jr. is offline   Reply With Quote
Old 10-15-2024, 04:52 AM   #2
Bill Grubbs
Member
 
Join Date: Oct 2002
Location: Magnolia, Texas
Posts: 406
Likes: 1
Liked 464 Times in 62 Posts
Default Re: Onan 12.5kw issues

Filter change?
Air?
Fuel?
Type of diesel (B20/no1/no2)
Bill Grubbs is offline   Reply With Quote
Old 10-15-2024, 04:46 PM   #3
Jack Zimmerman
Junior Member
 
Join Date: Dec 2001
Location: Clemmons, NC
Posts: 34
Likes: 0
Liked 10 Times in 5 Posts
Default Re: Onan 12.5kw issues

I've been told that a pretty common failure issue on the Onan QD generators is the fuel pump power supply on the main circuit board. The symptom is that the generator will shut off randomly and it may or may not restart. Our 10K unit did it when it got hot and as far as I know, the only permanent fix is to get a new circuit board. However, an easy work around and a way to diagnose if that is the problem is to run a jumper wire from the + battery connection on the side of the generator to the fuel pump power wire which is accessible through a small cover on the front right side of the generator. If that fixes the problem you'll know it's the circuit board. And if you use that method to run the generator until you get a new circuit board (like I did), you just need to make sure you disconnect the jumper wire when you shut off the generator or the fuel pump will keep running.
Jack Zimmerman is offline   Reply With Quote
Old 10-15-2024, 06:33 PM   #4
Mike Pearson
VIP Member
 
Mike Pearson's Avatar
 
Join Date: Mar 2007
Posts: 2,368
Likes: 566
Liked 1,738 Times in 532 Posts
Default Re: Onan 12.5kw issues

Mine has an 8k QD Onan. One time it would not start. I took the front cover off and the spade connector for the fuel pump had come apart probably from bumping down the highway. Plugged it back together and it start right up. I crimped the connection a bit tighter and it has been problem free. Replace the fuel and air filters. I change my fuel filter every other oil change. Change oil every 100 hours.
I would pull the front cover off and check all the connections before getting a new board.
__________________
Mike Pearson 2485 SS
Mike Pearson is offline   Reply With Quote
Old 10-15-2024, 08:10 PM   #5
Ed McLawhorn Jr.
Member
 
Join Date: Nov 2008
Posts: 291
Likes: 3
Liked 18 Times in 16 Posts
Default Re: Onan 12.5kw issues

Thanks everyone up to this point. Brushes came today, so I installed them. Not too bad to change and now I can rule them out as the issue. Gen started fine so I decided I would let it run all night. Hoping it helps as we?re getting ready to leave for Rockingham on Thursday.
Ed McLawhorn Jr. is offline   Reply With Quote
Reply



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 -4. The time now is 07:13 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright © Class Racer.com. All Rights Reserved. Designated trademarks and brands are the property of their respective owners.