an Onan microquiet 4kw. won't start. Checked all the obvious- fuel, fuel pump, and carb. The problem is " no spark" at the plug when cranking. I talked to Flight Systems who supplied the new control module we'd installed last summer. They say that the engine should produce spark while cranking even with the control module unplugged. The control module puts out a ground on pin 11 to kill the ignition when the stop button is pushed. There is no spark at the plug while cranking either with the module unplugged or plugged in. This Onan has a very small ignition module at the end of the sparkplug wire. Only one small low tension wire 'feeds' it. My question is "where does this wire go to?". A magnito/points setup under the flywheel? What kind of voltage should I find on this wire? I guess I'd like to know whether the ignition module is bad or if something is amiss in the magnito area. I've looked for replacement points online just to determine if this thing even uses points, never found any points listed for Onan.

Please reply with the full Model Number and Spec Code.

the model # is 4kyfa26100fyou'll have to give me a clue as to where the "spec" code is.

It should be "F" the last character in the Model Number. Ours is "K" and there's "K" at the end of Model Number AND a separate "Spec: K" on the label.I'm far from best equipped to help with this, but we have a couple ONAN gurus who still visit here. Meanwhile I'll look to see if I have a parts list then if F is set up same as K

any help will be appreciated. I didn't think I could have missed the spec #. Just checked again -- no spec # on the label.. pretty old unit, probably around 1999 or 2000.

I found this coil on a parts site and your spec is in fact different from ours.Very clearly NOT at the end of the spark plug cable, and he site specifies that we need to buy the plug terminal and boot separately in order to use this coil.

another ONAN question. | Good Sam Community

j-d
Explorer II
Apr 07, 2016
Glad you got it! For lawnmowers, I got a useful tip. The required air gap between magneto and flywheel magnets is hard to set up with the typical Feel Gauge. The tip was use a sheet of microfiche. Folded in two. Non magnetic, so it fits between the parts. The magnet tightens the clearance to spec (of the folded fiche). Just tighten the fasteners and pull the fiche out.
btcruzer
Explorer
Apr 07, 2016
I'm suspecting the actual magneto unit failed. One of the magnets was rusty and I did clean it up a bit but once I had the part and was in there to replace it-- no way was I going to re-assemble with the old mag just to test it. I had done some measuring on the old mag. before I got the new one, but forgot to measure the new one to compare. In any case - wasn't going to reinstall the old -- things are now happy in camper land
Gjac
Explorer III
Apr 05, 2016
btcruzer wrote:
The magneto did the trick ! Generator is reassembled and back in the MH !Son will be a happy camper.

O:-)
. Do you know what actually failed on the magneto? Mine was rusty but it sanded it down and recapped it.
btcruzer
Explorer
Apr 03, 2016
The magneto did the trick ! Generator is reassembled and back in the MH !Son will be a happy camper.

O:-)
btcruzer
Explorer
Mar 30, 2016
To sum things up, Microlite generators have had "solid state" ingition for many years -- at least back to 1996. The discharge voltage on the lead to the primary side of the ignition coil from the magneto should be approx. 16 to 60 volts AC. when measured with a digital Voltmeter. (Mine have very little and most of the time none.) We'll see tomorrow if this sucker will fire up tomorrow.
btcruzer
Explorer
Mar 30, 2016
I installed a new sparkplug. I have checked the ignition coil and it checks out ok. .5 ohm on primary and 1,100 on the secondary. Drat, I'd rather have to replace the coil than the magneto. The coil costs less and is far easier to replace.
The genset now is out of the RV and disassembled. Flywheel is off and I didn't lose the very small key. The magnets have some rust but have plenty of "pull".
Just now got the new magneto - next day service from Cummins. I thought getting the part would be a nightmare, couldn't find one anywhere on the internet. Called the local Cummins and got it within 24 hrs. Some days are diamonds.
I have cleaned the sliprings. Luckily, they looked very good, hardly any wear.
I'll start putting the thing back together tomorrow and let ya'll know how it works out. Till then thanks for the replys/ advice.
Generator_Jim
Explorer
Mar 30, 2016
Test the ignition coil first and replace the spark plug just for fun. Couple of possible internal problems; The magnet in the flywheel could have excessive rust and partially block the triggering of the magneto. The magneto may have shifted out of position. The magneto may be bad.
Since the magneto is under the flywheel, I recommend that an ONAN dealer do the job of replacing it. If you try it yourself, GET THE OVERHAUL MANUAL. When the flywheel comes off, a very tiny key tries its best to get lost. Be ready for it to fall out and under the unit. The key controls spark timing so it is necessary to have it.
When the flywheel is off, clean the sliprings and brushes using fine sandpaper (not emery paper) and electronic cleaner.
Have fun.

On Edit -- Using J-Ds serial number as an example, D is April and the 02 is the year of manufacture. The rest of the number is the actual serial number.
j-d
Explorer II
Mar 29, 2016
The manual I have doesn't match with that coil I pictured and you said you saw. It showed a coil under the flywheel like a rotary mower has.

Wish I could help more.
Gjac
Explorer III
Mar 29, 2016
I think by 1999 these gensets eliminated points. When my 1996 Kohlar died(no points) I found it was the coil. The magneto needs a gap also to work, I think I used a .030 feeler gauge to set it. Your manual will tell you what to set the gap at. I found it easier to use a non magnetic material like a match book cover to set the gap. I would buy a Onan coil rather than a generic replacement coil.
btcruzer
Explorer
Mar 29, 2016
that coil is like the one on mine, it actually is at the end of the cable - the terminal attaches at the bare end

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