79 Rude 100hp - no fire

[jdcarter]

Guys - my buddy has a 1979 100hp Evinrude thats getting no spark to the plugs... It has been running great up until yesterday - he was idling out from the boat ramp when it shut off and wouldnt fire back up - check the spark and there is none. Any help on where to start would be greatly appreciated!!

 

[emdsapmgr]

Re: 79 Rude 100hp - no fire

It is unlikely that all 4 spark plug coils failed at once. That engine has two power packs, each one feeds one head (two cylinders.) Unlikely both went out at the same time. So, I'd be looking at the timer base and the stator. Check your stator output according to the troubleshooting in the factory service manual. Both of these components are expensive, so some investigation will pay in the long run.

 

[jdcarter]

Re: 79 Rude 100hp - no fire

thanks emd - thats what I was thinking but wanted a little more input because there's no fire on any of the cylinders so I doubt the 4 coils and/or 2 power packs failed at the same time as well...
One other thing we were just discussing - he said sometimes the motor doesnt shut off when he turns the key off -he has to trim it up/down to make it turn off - so it may be something within the hiring harness (naked/broke wire) that could be causing it? or would the timer base or stator cause that as well?

 

[Chinewalker]

Re: 79 Rude 100hp - no fire

Could be the kill circuit. I believe that is the black wire with yellow tracer. As noted, highly unlikely that all four coils or both packs would fail at the same time. Check that wire for breaks/shorts, and also check the key switch while you're at it... Knowing he already has issues with the key switch not working, that's where I'd start.

A simple test - unplug the red plug at the motor, pull the spark plugs, plug them back into the boots, ground against block and spin the motor over by hand (rope). Check for spark. If you have spark with the red plug unplugged, you have an issue in the wiring harness...

- Scott

 

[jdcarter]

Re: 79 Rude 100hp - no fire

thanks Scott! We'll definitely check this...

 

[Bubbapeyregne]

can the motor be started by crossing the solenoid with the red plug unplugged without hurting anything

 

[racerone]

Yes, as long as there is a battery connected to protect the charging system.

 

[Crosbyman]

Bubba.... bets not to wake up old issues from 2010 start a fresh post with current issues you are having