Evinrude 85 HP - no spark unless compression is released ( `77 model )

[GpFinn]

Experiencing this weird issue.

engine has no spark with plug inserted.

If I remove the plug ( releasing compression ) then I get spark.

I have replaced the starter, power pack & rectifier.

problem still persists.

has anyone else seen this type of problem ?

Thanks a Mil for any tips.

 

[racerone]

The ignition ( spark ) system does not use 12 volts to produce the spark.----That is done by the electronic magneto spinning at the proper speed.-----New starter or used?-----When one of these motors cranks too slow there will be no spark.---Check wiring and test the battery is next to do.------Do ohm test on stator next.---Rectifier has to do with charging the battery.-----

 

[GpFinn]

The ignition ( spark ) system does not use 12 volts to produce the spark.----That is done by the electronic magneto spinning at the proper speed.-----New starter or used?-----When one of these motors cranks too slow there will be no spark.---Check wiring and test the battery is next to do.------Do ohm test on stator next.---Rectifier has to do with charging the battery.-----

It's brand new starter. suppose to a good one.
new battery 1000 amps

you are right about the speed of spin, because with plugs out ( compression released) it is faster spin, then I do get spark

 

[joereeves]

The engine must crank over at least 300 rpm in order for the stator under the flywheel to generate approximate 300 AC volts to the powerpack capcitor. This is why "all" spark plugs must be removed to obtain the highest cranking speed possible.

Normally, even brand new engines... with the spark plugs installed, when cranking, not all of the plugs will fire, but within six (6) revolutions, at least one will fire resulting in a vast increase of rpms which results in all of the other cylinders firing properly.

Note that checking spark with the spark plugs is a waste of time... a spark tester where you can set a 7/16" gap for the spark to jump in a must. That 7/16" spark should be a strong blue lightning like flame... a real SNAP!

If you have this type spark on all cylinders when cranking with all s/plugs removed, the spark is considered to be okay, HOWEVER.... visually check the stator under the flywheel to see if a sticky looking substance is dripping from it down upon the powerhead. If this substance exists, that would result in a voltage drop from the stator to the powerpack which in turn will result in weak, erratic, and eventually no ignition/spark.

If you have proper spark, the correct plugs (Champion QL77JC4 @ .030), good compression and a clean fuel system, the engine has to run.

What kind of problem are you having?

 

[fdrgator]

I agree, the problem it is not cranking fast enough----or it is not producing the necessary output from the charge coils or sensors. Bad charge coils (cracked or dripping goo) is a common cause. You have obviously done considerable guessing, as evidenced by replacing the starter, power pack, etc. Proper testing avoids a lot of unnecessary guesswork and waste of money. A DVA meter is an almost must-have tool to begin with.