1974 Evinrude 85 no spark, need advise

[mtatua]

OK, picked up this evinrude for $300 bucks. Pretty fair shape. Did all the routine maintenance, carbs, water pump, thermostat, plugs. Shes got 120 lbs compression on each cylinder, very nice there. Did the heads and exhaust housing, cleaned those out....etc, etc.

No spark now. Actually, intermittent spark on #1 only, tested at 7/16". Nothing on the others, and #1 is very intermittent. I did pull the plugs and touch to block, and they all do sp New battery, good cranking speed, NO voltage leaking in black/yellow wire. Stator is not melted, timing base turns freely. Wet plugs. Key turned on, no lanyard-kill on this model.

I did purchase a new CDI power pack, and here are some measurements I've taken per the CDI guidelines and the OMC service manual:
Brown to Brown/yellow: 200 volts (with DVA). Ohms around 580.
Black/white #1 to black/white #3: Ohms 6.8, DVA voltage .80
Black white #2 to black/white #4: same as above. Ohms shows low per CDI instructions
Black/white all to ground: 0 volts, ~200 ohms resistance when meter set on 200K (manual said set to HI ohms..?)
White/black all to ground: 0 volts, ~200 ohms resistance when meter on 200K.


Removed the yellow rectifier wires, no change. Ignition coils look good, no cracks, some rust on the metal surrounds. I've cleaned every ground I can find.

Flywheel looks good except for 3-4 chips in the trigger magnet. Its not loose.

​

I'm at a loss, I think its a timer base issue, but I'm not sure about the flywheel either. I have the tools/meters to check all this stuff, just can't quite follow what it all means.

Any help appreciated.

 

[racerone]

Some will argue-----I would get the battery load tested.-----I would take the starter apart for inspection.-----No money spent inspections to do and easy to do.

 

[oldboat1]

If you have the complete electrical harness/controls, think I would make sure the battery was strong (above), then sink the lower unit deep in a barrel and try to fire it up. Save the heavy duty testing until you have a sense of what it does and doesn't do (JMHO). If it runs, don't overdo it while celebrating -- will need a new impeller to be safe.

 

[mtatua]

Appreciate the responses so far. The battery is literally brand new, and the motor cranks really well with the plugs in and even better with them out. I will check the starter and double check the cranking rpms. I've had a couple of these V4's through the years and this one cranks as good or better than any.

I do have the muffs on when cranking and testing, hoping not to ruin the new water pump.

However, she doesn't even act like she wants to fire. Not even a hint of ignition. Thats why I am looking at the ignition system closely. And the fact that at least 3 of the cylinders won't spark on the 7/16th gap.

 

[oldboat1]

Shoot.

Sounds like you know what you are doing. Guess from here would be the power pack -- maybe test that first (oem manual or the CDI diagnostic instructions.)

 

[mtatua]

Final update for those interested: It was the timer base that was bad and a new CDI unit has it running pretty well. Check the voltages and ohms I measured in OP if you have something similar.