Trouble with 1998 15HP 4-stroke Evinrude

[FixMyMotor]

1998 15HP 4-stroke has me pulling my hair out.

Previous symptoms:
Would run for a mile or two, then lose power a bit, then quit. If you wait a minute it will restart and you can go again. We actually used it this way for part of the year, but that changed after it refused to re-start like it had been doing.

Current symptom:
Now it will start in the morning and you can run it at the dock, pretty much as long as you want. It runs smooth, has power. If you turn it off, it will not restart that day. Not kidding. No matter if you run it for 5 seconds or 5 minutes if you turn it off it will not restart that day, even 4 hours later. It will restart perfectly tomorrow, though. It starts very easily. Once a day.

What we've checked:
New plugs
New plug wires
Fuel pump is good
Water pump/impeller is good
New Stator/Charge coil 2 years ago
Temp switch seems OK

 

[racerone]

Is there spark for the plugs when it refuses to restart ?----And is it real spark.----Real spark jumps a gap of 3/8" ( 1 cm ) on both leads.

 

[FixMyMotor]

It started this morning and then I turned it off. Would not restart... no spark on my inline spark tester. Checked it at the high-voltage coil, too.

Here's a video of it running this morning and then not starting:
https://youtu.be/keB_tNwnMQ0

 

[FixMyMotor]

So today I had an assistant to help.

Tried to start, would not start.

Pulled top spark plug out, held spark plug threads against ground to check for spark. Turned key, it then sparked, motor started and ran with one plug. Turned off. Put plug back in. Now it would not start.

Pulled top plug back out, held threads against good ground, no spark this time. Motor did not run or try to fire.

Grabbed a voltmeter, cranked the starter, and verified stator is putting out voltage into the 4-pin weather connector that plugs into the power pack.

I guess we're down to it most likely being the power pack.