No Spark... sometimes..

Got a 1983 Evinrude 70 thats been giving me some trouble. Had an issue with rough starting and rough idle for awhile now and I have definitely narrowed it down to an issue with the spark but that's about it. Also probably not the coils or powerpack. Anyway after sitting overnight or until it gets cold the spark is gone, if you start messing with it and crank it over for awhile the spark comes back on a few cylinders and you can get it started but it will not run at idle you have to rev it up to keep it running. Only way to get it to run is to open it where it will run fine at 4500 rpm all day, getting it on plane is tricky though it will not rev up immediately, runs real rough for a while struggling to get over 2500 rpm but then like a switch is flicked it clears its throat and you're good until you shut it off again. Should also mention it leaves quite a trail of smoke when it comes back to life. Pumping the primer bulb has no effect and pumping the primer solenoid makes it want to die like if you were to choke it out.

So far I have checked compression 115 across all cylinders, soaked and rebuilt all carbs, cleaned and inspected fuel pump and lines (fuel pump and lines are 3 years old) replaced the power pack and swapped coils to no avail. Grounds and bulb have been cleaned. Removed the temp sender alarm thinking it was putting it in slow mode. Also tried to run it with the box disconnected to rule out anything in the box. I am using a gap spark tester and inline spark tester to confirm no spark. Timing light wont pick it up either when its acting up.

Any help would be appreciated this thing is driving me mad, would like to have it running for the 4th tomorrow too no pressure haha.

Compression is not encouraging.----Does spark jump a gap of 7/16" on all leads , yes or no ?---Have you checked starter / battery / battery cables ?

I was happy with the consistency of compression atleast.... Spark will not jump any gap, its completely dead...as of now. Battery cables are new of last year as well as battery. No idea about the starter age but it will crank it over at about 800 rpm.

Spoke too soon, left it alone for awhile and when I came back it fired right up except for the bottom cylinder isn't sparking so its running pretty awful.

what is the model number of this engine ?
because a 1983 dont have the S.L.O.W mode on the electrics.
1983 makes it a 49 cu in motor no the later 56 cu in. from 1986 onwards.....
if you made a mistake and is 1993 then its worn out with that compression for sure, it not good for a 1983, but totally worn out If it is a 1993..
Have you taken the flywheel off and checked for any cracked or broken wires from the stator ?

Have you checked the kill switch wires ?? and the switch itself ?
give it a try it with kill switch wire disconnected at engine end........

It is a 1983, wasnt sure if it had the slow feature or not but I thought I would be sure.

Some progress was made, got rid of the rough running part of the problem after discovering the bottom spark plug wire was "leaking" or grounding the block occasionally dropping spark from the cylinder when it did. Late night tinkering does pay off! saw it arching across in the dark.

I assume that you remove the spark plugs before checking the spark, if not, do so.

When this "No Spark" scenario exists, disconnect the black/yellow wire from the "M" terminal of the ignition switch. If with that wire removed, you have proper spark, replace the ignition switch. If no change in the spark..........

Visually and closely inspect the stator under the flywheel. That model has three (3) large coils incorporated within it, seperated equally that supply AC voltage to the powerpack's capacitor. Should that stator be dripping a sticky looking substance down upon the powerhead area, that would result in a AC voltage drop to the powerpack, which in turn would result in weak, erratic, and eventually no ignition/spark. If this situation exists (dripping), replace the stator.

Let us know what you find.

Have not checked the ignition switch yet but I did do a visual inspection of the stator and discovered a few drops of black goo along the underside of the stator on the port side of the engine. Not enough to drip on the powerhead but there are drops on the stator. I guess this means I need a new stator?

jn1440 said:

Have not checked the ignition switch yet but I did do a visual inspection of the stator and discovered a few drops of black goo along the underside of the stator on the port side of the engine. Not enough to drip on the powerhead but there are drops on the stator. I guess this means I need a new stator?

Click to expand...

Not necessarily..... the factory coats those things pretty heavily with the result that some look like they've been painted too heavy and runs have ocurred. Replace ONLY if you're absolutely sure it's cracked and starting to drip.

I tested the resistance of the stator according to the service manual I have and that was within spec for what the book said. Got 480 ohm across the plug going into the power pack.

Now here is where I may have made some headway with it, when I plugged the plug back in and it fired right up but eventually went out again. So I started fiddling with the plugs all over it and got it to spark again. Afterwards I went nuts with the Deoxit and it has maybe only quit once now. I'm thinking corroded connections may have been the culprit?

Did you remove the black/yellow wire from the ignition switch, then test for spark as per post #6?

I did unplug the red bulb and crank it over by jumping the starter to check for spark, would that do the same?