Johnson 90 HP Ignition Problem

[emeraldcozy]

I have a 1981 Johnson 90 HP. I lost the spark on one side of the motor and thought it maybe the powerpack. After replacing it I still don`t get a spark on those 2 cylinders. I was wondering what my next step should be. Is there an easy way of checking the stator ?? Or could my problem be the CDI ?? Any suggestions are greatly appreciated.
Thanks, Markus
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[Seasport]

Re: Johnson 90 HP Ignition Problem

You may have a stator problem. I think you have two sets of charge coils on that stator - one for each bank. If you have a multimeter you should check the stator resistance between the brown wire and brown/yellow wires coming from the stator to the powerpack (charge coil). Should be about 500 ohms for each set.

You should be able to swap the connections and see if the no fire condition swaps banks.

You can download an ignition troubleshooting guide from rapair.com. This has a lot of information on troubleshooting various ignition problems.

 

[emeraldcozy]

Re: Johnson 90 HP Ignition Problem

Thanks, Seasport. I will try that today. If it comes out to be bad, how hard is it to change one ? Is there anything I need to watch for when I pull the flywheel off ?
Also I couldn`t find the website you refered to. Could you please post a whole link ? I would love to be able to download a Manual.
Thanks, Markus

 

[Seasport]

Re: Johnson 90 HP Ignition Problem

Not hard to change. Just need to pull the flywheel. A manual will tell you how.

To find the ignition troubleshooting manual go to www.rapair.com go to Product Info, Downloads and you'll see it there.

If you do a google on "No fire or Intermittent on One Bank" you'll also find an online version. Not meant to paste a link here.

 

[emeraldcozy]

Re: Johnson 90 HP Ignition Problem

Thanks again, Seasport. I went out there yesterday and checked the ohms across each bank. It came up as 570 ohms on each side. So maybe my Stator is still good. I will check out the rest like it says in the manual.

Thanks, Markus

 

[DHPMARINE]

Re: Johnson 90 HP Ignition Problem

You might try switching the power packs side to side.Too many years ago to remember all the details,I had a V4 that the starboard pack was actiually klling the port spark.Only time I've seen it (28 years).When I talked w/OMC,they agreed it can happen.

DHP

 

[Seasport]

Re: Johnson 90 HP Ignition Problem

If you do a Google on "Troubleshooting OMC Power Packs and CD's" you'll find some more useful info.

Maybe you replaced the wrong pack? Hope you kept the old one

 

[emeraldcozy]

Re: Johnson 90 HP Ignition Problem

Ok, I went and replaced the key switch. That didn`t help. Replaced both coils on the bank that is not firing, that didn`t help. I took ohm readings across both banks coming from the stator both come out at 570 ohms. checked voltage coming into powerpack ran right around 270 volts on both wires. Anybody with anymore thoughts ??

thanks, Markus

 

[castaway68]

Re: Johnson 90 HP Ignition Problem

maybe try switching coils,,not likely 2 went bad at the same time,,but worth a shot,,how do the coils ground,right to block or is thee wires that ground them,if so maybe the wire has failed.

 

[reeldutch]

Re: Johnson 90 HP Ignition Problem

if you have 270v comming from your stator chargecoil, check the voltage from the trigger.

if the trigger is good to than you know it could be the pack.

dont forget the pins on the plugs (Connectors) can give problems.

 

[reeldutch]

Re: Johnson 90 HP Ignition Problem

also check the primairy coltage going out of the pp.

if you have 270 going in and noting going out and the trigger is firing your pack is bad.

 

[emeraldcozy]

Re: Johnson 90 HP Ignition Problem

what do you mean by trigger and how do i check that ?

 

[reeldutch]

Re: Johnson 90 HP Ignition Problem

trigger or sensor coil (same thing)

it sends low voltage to the pp so the pp knows when to release the high voltage from the stator to the ignition coils.

the trigger gets its signal from a slotted magnet in the inner hub from the flywheel.

 

[Seasport]

Re: Johnson 90 HP Ignition Problem

I'd say the timerbase (trigger as reeldutch calls it) is the next thing to check out. This is the thing that rotates under the flywheel (next to the stator) as the throttle is opened and closed. It has a series of coils that send a low voltage signal (0.5V) to the powerpack (or powerpacks in your case) at an appropriate time to fire each cylinder. The timerbase position determines the ignition advance as the throttle is opened.

You should measure about 40 ohms between the white wire and each of the four trigger wires (should be blue, green, purple & pink). Can you see any goo seeping out of this part. This is normally a sign of a failed unit.

Have you got a shop manual?

I also read this:

Engine runs rough on one bank (4, 6 and 8 cylinder engines with CD ignitions):
DVA check stator voltage to both sides. The readings should be fairly equal. If it exceeds 400 volts, replace the pack on the bank. If unequal, swap banks with the stator leads and see if the problem moves with the stator leads. If it does, replace the stator. Disconnect one of the black/yellow kill wires, AT THE PACK. If the problem goes away, replace the pack that was running smooth as is probably has a bad blocking diode.