Onan P-Series Ignition Module Replacement [Photos]

[cmitch 3]

I am tackling this same issue next month with my 1992 416-8 Wheel Horse. I found this part on Jack's Small Engines:

https://www.jackssmallengines.com/jacks-parts-lookup/part/onan/1660821?gclid=eaiaiqobchmi4qhctmbc6aivewkgch2nfgeyeaqyasabegkyfpd_bwe

 

I am personally not thrilled with Jack's small engines. I ordered a hydrostatic transmission from them for my 54" Cub Cadet and it barely lasted a year and 30 hours. They would not make it up so I have a 2009 Cub Cadet with a great Kohler engine but a shot hydrogear drive that I paid $579 for.

Edited March 30, 2020 by cmitch

[nycredneck 12]

I bought a new module because after installing a new coil that I knew was bad my 1988 518H still had no spark. It now looks to me like the module in my tractor is upside down, how can that be? Looking at the pictures here mine is definitely facing "down" . How did it run in the first place like that? I will turn the module over in the morning and hope to get spark. Frustrating several months, replaced coil and module and still no spark, perhaps it will start. Also took a picture of my old coil wiring before I took it off and that is different then what I see here, again, how did it run previously like that? A mystery for sure.

Edited March 31, 2020 by nycredneck

[lynnmor 8,591]

29 minutes ago, nycredneck said:

It now looks to me like the module in my tractor is upside down, how can that be? Looking at the pictures here mine is definitely facing "down" . How did it run in the first place like that?

I would like a photo of that before you change it.

[nycredneck 12]

Will take one tomorrow after I finish the brake job on wife’s car. 
Hope I am able to post pics on this site. I need that url link to photo which doesn’t always work for me. Maybe  I’ll get lucky and tractor will fire up!!
 

Edited March 31, 2020 by nycredneck

[nycredneck 12]

After turning ignition module 180* I am happy to report I have spark. It seems the timing may be off a little because it still not starting, fuel is there and it backfired a couple times plus it pushes out the carb also. The more serious issue is the new coil seems to get hot which is a big deal because that was ( I thought ) my original problem, the old coil was partially deformed from excessive heat and it was the first thing I replaced. Could the voltage regulator be a problem causing this? Down the rabbit hole I go... glad that some of you will follow me, thanks.

[rwolf15241@yahoo.com 0]

I'm working on a Onan 24hp, I have the kit, looking for info how to install it!! can't see the pics!!

 

[lynnmor 8,591]

22 hours ago, rwolf15241@yahoo.com said:

I'm working on a Onan 24hp, I have the kit, looking for info how to install it!! can't see the pics!!

 

 

 

Here is a brief description, come back and ask questions as needed.

 

Remove the blower housing, then the flywheel.  The flywheel can be difficult without the proper puller, one can be made from a piece of steel with 4 holes to match the holes in the flywheel, and then add a hole in the center with 1/2" threads.  Loosen the center flywheel bolt two turns and then apply the puller.

[rwolf15241@yahoo.com 0]

I have mine installed on the Onan 24HP. It  came with Points. So I had to change to timing cover to mount the module. Where does the white wire from the points go?? I see the black wire from the condenser goes on the positive of the coil!!

 

Thanks RW

 

[lynnmor 8,591]

2 hours ago, rwolf15241@yahoo.com said:

I have mine installed on the Onan 24HP. It  came with Points. So I had to change to timing cover to mount the module. Where does the white wire from the points go?? I see the black wire from the condenser goes on the positive of the coil!!

 

Thanks RW

 

Since you eliminated the points the wire can also be eliminated.  With the conversion to electronic ignition, the condenser and the coil may be of the wrong values and not work correctly or fail early.

[rwolf15241@yahoo.com 0]

This is the kit I have for the conversion, you said I should eliminate the white wire for the point so where  does the new condenser connect to the positive side of the coil??

 

Thanks RW

[lynnmor 8,591]

1 hour ago, rwolf15241@yahoo.com said:

This is the kit I have for the conversion, you said I should eliminate the white wire for the point so where  does the new condenser connect to the positive side of the coil??

 

Thanks RW

Use the terminal that is right next to the + sign.

[ti-jean 45]

Nice poste thank's from St Colomban North of Montreal Quebec Canada 

[CD Long Jr 195]

On 7/31/2017 at 8:50 AM, Duramax7man7 said:

Okay, 

INTRODUCTION:

 So if you've problem solved all other aspects regarding your non-starting Onan engine with electronic spark control and come to the conclusion that you need to replace the Ignition module, keep reading. This is a decent step by step and doesn't require the engine to be removed the from the tractor. Although it might be a little easier to work on while on a workbench.

 The part numbers for the Module and ring if needed are below:

Ignition Module: 166-0785
Spark Ring: 166-0767

Here is a list of the tools that I needed to complete the job from beginning to the end. They are named from left to right in the photo with the tools at the top of the photo last from top to bottom.

TOOLS:

[From left in Photo]
1. T25 (for the stator screws but also may be three 5/16" head screws)

2. Phillips and Flat Head Screw Drivers
3. Needle Nose and standard slip joint pliers

4. Flywheel puller with 2 5/16" x 18 grade 8 bolts and washers (mine is technically a steering wheel puller)

5. 7mm and 5/16" deep well 1/4" sockets

6. 3" 3/8" drive extension, 3/8" socket 3/8" drive, 5/8" socket 1/2" drive and 5" 1/2" drive extension. 

7. 1/4" Socket Driver
8. 5/8" open end box wrench
9. 3/8" and 1/2" drive ratchets

[Top of photo- top to bottom]

10. Flash light (optional but very helpful at times)
11. Pry bar (used to lock flywheel from turning)

12 1/2" Torque wrench

13. Old Tooth Brush (for cleaning of dirt if needed)




PROCESS:

- Obviously the first thing to do for safety sake is to shut of the fuel at the tank and remove the battery cables
- Next, remove the two screws that hold the fuel pump onto the shroud, move the pump off to the side and replace the screws into their holes for safe keeping.
- Carefully pull the fuel pump away from the shroud enough to work the hose clamp out and use the pliers to pinch the hose clamp and remove the vacuum line for pump. 




- Tie the fuel line, wiring harness, choke cable and battery cable all out of the way towards the rear of the tractor allow easy access to remove the shroud.



- Next remove the air cleaner box cap, then air cleaner cap and air cleaner tray by removing the three 5/16" screws from the carb and the two 3/8" screws from the tray and put all aside and out of the way. 

NOTE: Close the Choke all of the way and stuff a clean paper towel into the top of the carb to prevent debris contamination.

- Next, twist the air filter box bracket to the left (right side up and left side down) to clear space and use the 7mm, 5/16" and 1/4" socket driver to remove the black condenser wire, the red and black ignition module wires and the yellow ignition switch wire from the coil and then remove the coil using the 3/8" socket. (optional as it can be kept on the shroud but makes it a little more difficult.)
-  Next loosen the rear cylinders top shroud and engine hoist mount bolt with the 1/2" 3/8" sock and extension. (no need to remove the bolt as the shroud just needs to move freely. 
- Next, locate the wire retaining clip at the top of the shroud by the coil and open it up so the oil pressure sensor, stator and ignition module wires can all be removed when taking out the shroud.
- Last step before removing the shroud is to disconnect the throttle to gov arm spring and the throttle cable using  the 5/16" socket and driver.
-Next locate all of the shroud bolts and remove using the 3/8" socket.

 

 

- To remove the shroud, pull the bottom out first and then shift the entire piece upwards while working it from underneath the rear cylinder shroud, underneath the filter box bracket and over the flywheel on the left side. Work slow so you don't bend or brake anything and it will come off pretty easily. 
- Although everything was fairly clean in comparison to other engines at this step, my shroud was dirty and this can slightly decrease air flow which is important to maximize and keep optimal with an air cooled engine. 
 

 

 

So I took mine outside and pressure washed it to give it time to dry completely before reinstall. 

 

Shroud off... 

 

 

 

- Next, place the pry bar into the fins of the flywheel and lock the flywheel in place by placing the handle of the pry bar under the foot rest. Then use the 5/8" sock, 1/2" extension and loosen up the flywheel bolt about 3/8" -1/2" out of the hole. This needs to stay mostly in as a pressure point for the puller.

- Next, remove two of the flywheel grill center bolts and then use your two 5/16" grade 8 bolts and attach the puller to the flywheel while keeping the puller parallel to the surface of the flywheel to allow equal pulling pressure on both sides of the puller while cranking on the center pressure bolt on the puller. 



- Now it's time to remove the flywheel.  It may be a good idea to use the 5/8" open ended box wrench to stop the flywheel bolt from turning while cranking on the puller center bolt. 

- It should only take a 3-5 good cranks after finger tightening the center bolt and the flywheel will give a good pop and be ready to be pulled off. Don't forget about the flywheel bolt first!

 

- Next, carefully pull the flywheel off of the crank being very careful not to get caught on the stator itself. 

 

 

My flywheel was pretty dirty on the inside and between the magnets so I felt it necessary to use the toothbrush and air gun to clean it out. 

 

- Now you'll need to remove the stator by using either 5/16" socket or T25 torque bit or driver. 

 

- Next, set the stator off to the side securely on a clean rag or similar. Underneath, you'll see the ignition module on the bottom side of crank. There are two 5/16" head machine screws. Remove those and open the wire retaining clip on the side of the gear cover and the module comes right off. Make sure not to lose the black rectangular insulator that goes between the module and gear cover. That needs to be there. 

 

I'm not 100% sure but I have a theory that these modules may potentially go bad from getting covered with grass and debris over time from not blowing out the air shrouds with a leaf blower or air gun after each use. This debris builds up enough to cause insulation around the module. The module being an IC (Integrated Circuit) is designed to handle only so much heat. Over time the extra heat and expansion with contraction when cooled back down causes a when point in the modules chip circuitry and eventually breaks. Thus causing the engine to shut off during operation for the first time. Once the engine cools, the chip materials contract, allowing the circuit to bridge again only until the engine heats up enough to break that signal and then becomes a cycle until replaced. 

- Moving on.. While everything is out, if needed (or your OCD kicks in), clean the cylinder heat syncs and general area before re-installation of the Module, Stator, Flywheel and Shroud. Mine wasn't to bad so I quickly used the toothbrush and air gun to break free any layered gunk and blew it off with air. 



-Next, once the insulator, module (and spark ring if chosen to) and stator are all reinstalled and screws all snugged up, carefully put the cleaned flywheel back on, install the flywheel bolt with a tiny tad of anti-seize on it and use the pry bar again in the flywheel fins but with the handle on top of the foot rest and use the 5/8" socket, extension and 1/2" torque wrench set to 55lbs and tighten up the bolt. 

 


At this point, go ahead and reinstall the Shroud making sure that the fuel pumps vacuum line is accessible through the front hole in the shroud, along with the shroud bolts, coil, coil wires (spark, condenser, module and switch) and tighten rear shroud bolt. 

NOTE: Yellow Switch wire, red module wire and black condenser wires all go on the Positive coil terminal (7mm nut) which should be on the right side of the coil. Only the black module wire goes on the left terminal. 

 

Connect the throttle to Gov arm spring, throttle cable, install the fuel pump vacuum line again and replace mount screws. 




- Lastly, re-install the filter tray, remove the paper towel from the carb, along with installing the air cleaner, pre-filter and clean cap and shroud to filter tray pipe. Then connect the battery and turn the fuel back on. 



 This should get you going again. 




 I think that I got everything but please feel free to comment on anything that I missed as far as documenting the steps or ask any questions about the process. 

 Hope this helps you see that it's not that bad of process to replace the ignition module (And spark ring if needed as some recommend replacing the module , ring and coil all at the same time).

I had to first remove this module from a P220G that was on my bench and awaiting repairs but the whole process took me a few hours. A good Saturday Morning task to be up and running by the afternoon for some work before the heat hits. I also ran the tractor for well over and hour after install to insure all was well. I went from a warm up process of idling and then a lap around my property. Did that a few times while repairing a cutting deck and then installed the cutting deck and mowed the lawn. No issues. Ran great! 

Take Care and God Bless!

Andrew C.

 

Why can't I see the pictures?

[rmaynard 16,844]

1 hour ago, CD Long Jr said:

Why can't I see the pictures?

It's an old post (2017). Links are probably no longer available.

[wallfish 19,152]

1 hour ago, CD Long Jr said:

Why can't I see the pictures?

I'm guessing the original poster deleted those pics to make more space for others. 

[lynnmor 8,591]

2 hours ago, CD Long Jr said:

Why can't I see the pictures?

 

There are a few photos here that may help you.  If you ever have an over-speeding condition this thread will be a help.  Of course you wouldn't need to get in the timing case for your module replacement.

 

Take some photos of the wire routing as you disassemble. 

 

I would use some caution when pulling the flywheel, use your Onan Service manual for instructions.  I made a puller that uses all four threaded holes in the flywheel, using only two holes is risky if the flywheel is stuck.  The flywheel is torqued to 55 lb. ft., again use caution holding the fins when removing and tightening the flywheel bolt so you don't break a fin.  The flywheel bore and shaft is to be dry when installing, I use a rust preventer on it but wipe it till it is almost dry.

 

You may not have the thin insulator under your module, if there is none you can buy from OnanParts.com part number 166-0786, or make one from gasket material.

[Handy Don 15,811]

1 hour ago, lynnmor said:

I made a puller that uses all four threaded holes in the flywheel,

I copied you on this and it worked a treat!

[CD Long Jr 195]

3 hours ago, lynnmor said:

 

There are a few photos here that may help you.  If you ever have an over-speeding condition this thread will be a help.  Of course you wouldn't need to get in the timing case for your module replacement.

 

Take some photos of the wire routing as you disassemble. 

 

I would use some caution when pulling the flywheel, use your Onan Service manual for instructions.  I made a puller that uses all four threaded holes in the flywheel, using only two holes is risky if the flywheel is stuck.  The flywheel is torqued to 55 lb. ft., again use caution holding the fins when removing and tightening the flywheel bolt so you don't break a fin.  The flywheel bore and shaft is to be dry when installing, I use a rust preventer on it but wipe it till it is almost dry.

 

You may not have the thin insulator under your module, if there is none you can buy from OnanParts.com part number 166-0786, or make one from gasket material.

I did find a good video where the guy is replacing one on a 520. Couldn't figure out how to post it. Don't know if it'll work or not. Wheelhorse 520; Engine Work / Quits When Hot / Ignition Module

 

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