'68 Johnson electrical trouble

[BadBowTie3]

'68 Johnson 85 H.P. V4AL-20A-
The motor starts strong and runs strong for 30 seconds. It will then die and refuse to start for 20 minutes or until it cools off. This is what I have done thus far-New: fuel, fuel lines, primer bulb, fuel filter, fuel pump, cleaned carb, new plugs, new coil, new engine wiring harness, set the points, cleaned stator contacts, and hit with hammer (the latter was inefective yet fulfilling).

It appears the spark goes away after the initial 30 sec of operation. I am ready to take it to a mechanic but hopefully you all will provide a different perspective. Thanks.

 

[Willyclay]

Re: '68 Johnson electrical trouble

I saw in your other thread that you repaired the wiring harness. I have a 1968 Johnson 100HP with similar problems. FYI, forum guru Joe Reeves told me OMC changed suppliers of wiring harnesses for 1968 and the problems did not show up for many years. My engine harness has badly deteriorated insulation on most wires and a replacement harness is NLA. My only option is to make a new one. Good luck with yours!

 

[F_R]

Re: '68 Johnson electrical trouble

Isolate the trouble WHILE it is malfuctioning. Disconnect and unbolt the coil, then unscrew the spark wire from the distributor cap. Then remount the coil and rig up a spark gap off the wire that you took out of the distributor cap. Crank engine. Do you have sparks?? If you do, everything is OK up to that point and your trouble is in the distributor or spark plug wires. But if no sparks, something is breaking down before that point.

 

[BadBowTie3]

Re: '68 Johnson electrical trouble

WillyClay- I found a harness online for $150 or so..but after I built a new one from scratch, which cost around $80 after I bought everything.

http://www.ebasicpower.com/pc/CDI41...ss, Johnson, Evinrude 68 85 HP Outboards.html

 

[BadBowTie3]

Re: '68 Johnson electrical trouble

F R-
I am unsure how to rig up a spark plug gap. Does that mean hold the dist. end of the coil wire near ground to see if it sparks? But do this after it has run and died?

 

[F_R]

Re: '68 Johnson electrical trouble

Yes. But I absolutely HATE getting shocked, so I would use something other than my hand to hold it near ground. Hold it a little more than 1/4" away.

Yes, after it has died. After all, you know it is working if it is still running.

 

[BadBowTie3]

Re: '68 Johnson electrical trouble

The coil is not producing spark after it cuts off. So then the issue is before the coil. I am looking into the Thermo switch, it's name alone makes it suspect...

 

[Willyclay]

Re: '68 Johnson electrical trouble

You are in the best hands possible with F_R posting in your thread so I will butt out. However, thanks for posting the link about your wiring harness source. Good luck!

 

[BadBowTie3]

Re: '68 Johnson electrical trouble

FR- is it possible the engine is heating up and cutting out because of the thermo-switch?