I believe my coil is bad on my Onan 4BGE generator

I hear ya, David. I tried working on this thing "in place" for a while but even pivoted down it is hard for me to get on my knees and work on the thing. It was so much easier pulling the unit out to work on it. It was not as bad to pull out as I thought. But I wish these things were designed to be removable or accessible a bit better than they are.

Ideally, I'd like to see them on rails so that the entire genset can slide in and out of the compartment.

Steve

Steven, I'm glad you have yours running again, mine went in a 3 start Onan shop in Oct, out and used for 1.5 weeks and back in the shop Jan 13th. Everyone seems to know the problem but Onan is still looking into the solution.

I wish I was young enough and strong enough to pull mine and do my own repairs. Count your blessings and carry on.

David

If you want to follow the whole saga, it is here:

https://www.smokstak.com/forum/showthread.php?t=176987

However, I have the genset running. In the end, nothing was wrong with the unit. The coil tested out fine, and while the ignition module failed the test described in the Service Manual, it passed a test suggested by Len K over on the SmokStak forum. I cleaned all terminals with a wire brush, hooked everything back up, and the genset runs like a clock.

One thing that is strange about my genset ignition control module is that most modules have only 2 leads, a red and black lead. The black lead goes to the negative post on the coil, and the red lead goes to the positive post on the coil.

But on mine, someone has, very professionally, spliced the red lead into 2 leads, and one has resistor and goes to the coil, and the other has a capacitor and goes to ground. The wires have actual printing on them "T1+" and "GND", so this does not appear to be a hack job, but some kind of commercial installation.

The folks on SmokStak say this is a "Pi Filter" for RF noise suppression. Onan does not think the splice should be there (from them), so my suspicion is that Winnebago made this modification to the unit to prevent RF interference with on-board electronics. I have an email in to Winnebago to find out. Not that it really matters at this point - the unit runs fine once again as it always has in this configuration.

I don't have an Onan but a Kolher and have had several issues with it and don't know if this will help or not. Does your model have a magneto? The thing in your photo looks like an ing module that connects to your coil. There is a gap that has to be maintained between it and the magneto I used a match book cover to set the gap. It is magnetic and was hard to use a steel feeler gage. This system replaces the rotor and points on the older system. If there is no gap just like points on a old car or lawn mower there will be no spark even if the coil is good.

Well. Today was a good day, all things considered, I think.

We had nice weather, so I went and fetched the RV out of storage and parked in my driveway and got the genset side of the generator jacked up and on jack stands and dropped the generator on its hinges.

Pulled the two bolts holding the ignition control module in place, and....it would not come out. I tried rotating the engine by the 3/8" hex in the nose of the genset, but no matter how I tried, I could not find the right angle to pull the module out! More on this later.

Meanwhile, while I could not pull it out, it sure as hell goes in, because I let go of the bracket and POOF it fell down into the genset housing. While I still had ahold of it from its cable, I could not get it out of the genset no matter how I tried.

So, I pulled the entire genset out of the RV. Turns out this was actually pretty easy. I went and bought a 1000-pound rated $10 4-wheeled moving dolly from Harbor Freight, and positioned it under the genset and blocked up 4x4s until I was nearly under the genset floopan. Then I jacked it down onto the blocks. Then I went under the RV with the jack and removed the hinge keeper plates, jacked the inside of the genset to lift it off the hinges, and then slowly let it down onto the blocks. Then I was able to wheel the set out of the RV compartment.

All of the major connections (battery, fuel) were easy to get to and disconnect, and the main AC output terminated in the roof of the compartment in a junction box that was accessible from under the kitchen table bench seat, so it was easy to disconnect that trunk and then wheel the entire genset to my garage. I got the neighbor to help me lift it up onto my workbench:

On the workbench:


Gee, it's much easier to work on a generator when it's on a workbench!

So I made myself a little fishhook out of a length of wire and was able to grab one of the mounting bolt holes on the ignition module bracket and finally was able to get the bracket back out of the housing. But I still could not get it out, no matter how I tried to work it between two fan blades!

It won't come out:


So I slowly turned the engine with a wrench, and then I noticed that one, and only one of the fan blades is slightly shorter than the all the others. With this fan blade in front of the module, the module comes out easily!

The short fan blade:


So, now I have the module out of the genset.

Module out of genset:


And with the module out of the way, I was able to turn the motor completely and lo and behold, my ignition rotor is there and completely intact!

One end of the rotor:


So, is this module wired up properly?


So, it appears that my rotor is intact. So that is not the problem. The next step will be to figure out how to test the ignition module itself.

This replacement part:
http://www.partsfortechs.com/asapcar...nan-p-350.html

Does not have 3 leads coming out of it like mine does. Why?

So, the good news is my rotor is intact so I don't have to separate the generator from the engine. The bad news is I still don't know why I'm not getting any spark.

Also, I do not know how to make sense of this:



Make certain of coil polarity: the negative (-) terminal connects to the ignition module (black lead), and the positive (+) terminal connects to the ignition module (black lead), and the positive (+) terminal connects to a battery positive source within the control, to the ignition module (red lead), and to filter capacitor C4.

This passage seems contradictory - it says that the black lead of the ignition module connects to both the positive and the negative terminal?

I think it is probably a typo and it should probably read like this:




On further investigation, my ignition control module is strange.

The module itself has a red and black lead, but the red lead appears to be spliced somehow. I noticed it when I pulled back the white thermal insulation.

One of the splices is labeled "T1 +", and the other labeled "GND", which is where they both appear to be hooked up.

My module does not seem to jive with the Service Manual description.

What is the black thing with 4 terminals on it that attaches to the genset housing above the starter? (already found out, it is the battery charge resistor)



Steve

So I did some testing last night on the ignition control module. I am not getting alternating 0/12 VDC from the module. So, either the module is shot or the ignition rotor is broken.

Looks like the module can be pulled from the top of the genset without cracking it open, and then I can look down inside with a borescope and see if the rotor is intact. With a little luck the module is bad, but I doubt it.

Steve

https://www.onanparts.com this fellow can help you with the gen.
This site has leftover obsolete parts.
https://www.srsoemparts.com

They can break off.

I am looking at this one:

https://rich.homeunix.com/gravely/engines/onan/gen-set/965-0528.pdf

It says the control module arms should never need service over the life of the genset. :)

They do provide a way to check it though.

Steve