1986 Johnson 15hp weak spark

[sahendo]

i have a 1986 15hp Johnson electric start outboard, model #J15ELCDE just recently got it, don't know much about it, i did get it to fire for a couple of seconds several times, but would not stay running, i know it is getting fuel, but the spark seems to be weak, from the research i've done it says the spark should jump half an inch, mine barely jumps a 1/4 inch on 1 of the cylinders and even less on the other! i was wondering if anyone had any ideas on the most common cause of weak spark???? just a guy loking to go fishing! any help or suggestions would be greatly appreciated!!!!!

 

[jakedaawg]

I would start by terting stator output with a peak reading voltmeter? do you have a manual?

Wait, I take that back. I see it is an electric start. Have battery load tested first and then go to stator output test.

 

[kbait]

Compression should test to 90+ on each cylinder and be w/in 10% of each other. If spark jumps 5/16" w/blue bolt in open air from both plug leads, call it good. Champion QL77JC4's gapped at .030". Check ground connections from CD box and coils and make sure they're clean/tight. Google 'leeroy's ramblings' to find all you'll ever need to know about your motor, and servicing it.

Good luck, and welcome aboard!

 

[sahendo]

Just wanted to let other people know. It was the (power pack), evidently they can go bad at any time. It fired a couple of times for a few seconds and that was it!

 

[oldboat1]

running OK yet, right? (Thanks for the return post!)

 

[sahendo]

I know it took a little long, but I put that motor on hold because I got hold of a different motor that was already running, thanks to everyone for the help!