1986 50 hp Ignition From .....

[JDusza]

Hell......o,
Been arguing with a 50 hp ignition all week. OA987473.
Replaced a bad switch box and now have 38 to 40 vdc at all three coils measured with a DVA and meter.
Airgap spark test shows spark to jump 1/8" but not 1/4". I want to see spark jump 7/16" to 1/2".
So, tell me if I'm on the right track to replace coils and spark plug wires.....
Thanks,
J

 

[Faztbullet]

Re: 1986 50 hp Ignition From .....

No... wrong track, replace the stator. The capacitor in the switchbox is not getting sufficient charge from stator, so when trigger tells box to fire the voltage discharge is too weak to be stepped up to around 25KV

 

[JDusza]

Re: 1986 50 hp Ignition From .....

Thank you. You mentioned this before, Faztbullet. Thanks for hanging with me. This is driving me nuts. I have a hard time believing the stator can fail "softly". There's nothing to it for moving parts. But, the fact that this was underwater, I supposed the stator can be corroding in the manner of the steering cable, appears fine and rotting inside....
I needed to understand how this goes. So, the trigger will let an insufficient amount of energy through? Nuts! I also thought the 38 vdc at the coil was a strong enough signal. Any idea what I should see at the coil?
Thanks again,
J

 

[carholme]

Re: 1986 50 hp Ignition From .....

Well, I guess we can presume that you finally got your flywheel on as you didn't bother to respond to your last round of posts.

Gerry

 

[gonefishy]

Re: 1986 50 hp Ignition From .....

The mercury troubleshooting manual says a DVA reading of at least 150V on the primary coil terminal. You need a DVA meter which gives a peak reading not a DC reading.

 

[Faztbullet]

Re: 1986 50 hp Ignition From .....

So, the trigger will let an insufficient amount of energy through?

The trigger does just what is named, triggers the SCR's in switchbox, it does not care what the capacitor voltage is.

 

[JDusza]

Re: 1986 50 hp Ignition From .....

Got it. I can see this.
The trigger is released by a set of magnets coming around so they don't care about voltage level. They're just triggers, switches. Okay. The original switchbox was indeed bad for I was getting nothing at the coil. The new switchbox was letting the 38 v go through.
The flywheel question is answered as I went back and took a closer look I found TDC and re-evaluated the reading at the index and I can believe it is at zero with some adequate tolerance. There is a dwell at the top of rotation that you can feel, so I gave up that argument.
The spark test is another one that I let mislead. There is spark, but, it won't jump more than 1/8". It will fire the plugs against the case. And yes, under compression, sparks are harder to generate.
So, off to Statorville for the first of perhaps many visits. This was a good one.
The minimum of 150 is acknowledged. I was getting the 38 to 40 mentioned. I must be mis-interpreting what CDI troubleshooting is saying.
I got it.
Thanks, Faztbullet for seeing me through! I owe you one!
J

 

[CharlieB]

Re: 1986 50 hp Ignition From .....

Before you spend the money on a stator, check cranking speed as a low cranking speed also will not allow the stator to generate sufficient voltage for the ignition to create a hot spark.

Minimum cranking speed is 300 RPM, if your motor (and starter) have been underwater, you may need to clean and lube the starter, double check that the starter solenoid is making good contact.

Once you verify cranking speed, retest stator output, THEN decide of it is still low, order that stator.

 

[JDusza]

Re: 1986 50 hp Ignition From .....

Aye!
With compression, the cranking speed comes and goes, indicating the starter should be gone through. Solenoid is making a good snap. To ensure good cranking effort, I have been looking at spark without compression. The flywheel is rotating plenty. The stator output remains questionable and spark weak at cranking speed.
J

 

[JDusza]

Re: 1986 50 hp Ignition From .....

Faztbullet! You nailed it with the stator!
Before the swap, voltage to the coil was about 38 vdc.
After the stator change, the voltage to the coil was 190+vdc.
The stator made the difference.
Now, ... still won't start.
The starter has no guts; won't push through compression strokes. I opened it this afternoon and, voila!, Chunks and dust! One of the magnets is shredded and the housing retaining the springs and brushes is broken so, at least one of the brushes isn't brushing. It doesn't spin freely. Water may have frozen in the housing and cracked it.
So, more parts!
Thanks, Forum, for the help! This has been one strange outing.
J

 

[Faztbullet]

Re: 1986 50 hp Ignition From .....

The ADI system is a really easy ignition system if you understand how it works.......