Switch box troubles, what to do next?

[Captain Mustard]

Got a old (junker) double eagle with a 1991 90hp (3cyl) Mercury OD049182. Runs but intermittent boggin down.
When I got the boat I was thinking carbs or fuel delivery, so I did the following:

-new plugs
-rebuilt fuel pump and filter
-replaced ALL fuel lines
-rebuilt carbs
-new gaskets for reed blocks
-Compression ok (cyl 3 is on the fence of being out of range [135,130,120])

Still the same symptoms, so moved on to electrical:
-Stator and coil packs show correct passive resistance
-Disconnected rectifier to eliminate that from being a problem
-DVA on Stator is around 300V (which I think is right)
-DVA on cyl1 = 180V, cyl2 = 240V, cyl3 = 0

So, I think it must be switch box.
Got a Sierra switch box and I was so exited to see all cylinders firing, DVA readings were 220V on all cylinders....this was for a minute, then it just died abruptly. Never again did I see anything from the switchbox.

Scratched my head for a bit....
Checked everything again, everything checks out as before except nothing on coil primary for all cylinders.
So I hooked up the old switch box again (hanging off the motor with ground screwed in)... to my surprise all cylinders firing with DVA at 180V (running right).
Scratched my head a bit more...
Wiggled every wire that is reasonably accessible while running to see if there's a break in a wire..no change.
Hooked up the 'New' switch box again, still nothing. Checked kill line (even disconnected), seems fine.
Scratching head...
Took the 'New' switch box off, installed 'Old' switchbox and engine runs. But cylinder 3 went from 180V to 0V (DVA) while I was checking...basically back at square one; intermittent fires.

I took the switchbox back to the store...probably gonna be 200 bucks down the drain, but store owner said he'd talk to sales rep at least.

Looking for help please.
1.How do you actually check the trigger? I have checked resistance and it is in spec (1k-ish). With the meter on resistance I see a quick drop while spinning fly wheel by hand on each 3 lines, seems appropriate.
2.Do my DVA readings seem reasonable? CDI says 180-400V.
3.Is there anything else I can check?
4.What should DAV readings on the stator lines be? Ground to red and ground to blue (although my wire looks more greenish)

I'm an electrical guy by profession, but outboards is new for me. I like to learn but I like to fish too Any help will be much appreciated.

 

[GA_Boater]

Find your motor in this guide and starting checking per the procedure - http://www.cdielectronics.com/wp-content/uploads/2013/02/CDI Troubleshooting Guide - 2012.pdf

 

[Captain Mustard]

Thanks GA_Boater, thats a great resource.
I didn't get very far before discovering the trigger is not meeting spec
Any trigger to engine ground is 15k ohms, which should be open according to that doc.

I was afraid of this as I don't have a flywheel puller and it means more parts to buy.

I also suspect the stator too, as the red to ground is 100 Ohms and should be either 75-90 or 135-165 depending on glued or bolted in version. Is there a way to identify the stator without pulling the flywheel?

I suspect its the glued in version as the blue to ground reads 3.6k Ohms

 

[Captain Mustard]

I've been trying to follow a Seloc manual, but it covers 1965-1992 3 and 4 cyl....so its not always specific to my engine.
according to the Seloc blue to ground should be 90-140, and red to ground 3.6-4.2k

But my readings show red to gnd 100, and blue to gnd 3.6k

Now I'm really uncertain :facepalm:

 

[Faztbullet]

Your stator is fine....wht/blk is common so measure from it to the brn,wht and purple wires and should be 800-1400ohms

 

[Captain Mustard]

thanks, what do you think about 15k from brn/wht/purple to engine ground?

Trying to track down a flywheel puller now, i suspect glued magnet damage now
Might need to cut my losses soon with this motor, at least I learned a lot

 

[dawwgman]

Disconnect your idle stabilizer if it has one and try it.

 

[Captain Mustard]

Just an update, if anyone is interested. I got my flywheel puller and the flywheel is off, 3 of 6 magnets cracked in half...1 still attached, 1 half attached , and 1 fully detached.

I think some damage may have been done after I saw one broken magnet and foolishly and carelessly tried to jar the flywheel off without the puller. Will never do that again knowing what I know now.

Stator and trigger visually look fine...and resistance readings are as before...so I think a new flywheel and switchbox may put this motor back in water.

On the hunt for a new flywheel...ebay has some that seem to fit. I wish i could replace the magnets but from what I read on this forum its not recommended and theres no way to buy replacement magnets.

For anyone who has been through this (if flywheel is my only problem), is this just a plug-n-play job? Or do I need to tune some timing for the replacement flywheel?

 

[Captain Mustard]

Does the edge of the stator look ok, theres a small amount of plastic 'chipping', but it might be normal?

 

[merc850]

If the chipping bothers you mix up a small amount of epoxy and clean and apply. Clean those iron filings from the laminations; the flywheel just drops onto the crankshaft with the keyway aligned with the key on the crankshaft. I usually drop it on then turn it around 'til it falls down. Tork the nut to manual ft.lbs.