Late 70's Evinrude 140 weak spark

[MaPaHa]

This is an update to another thread I had going but seems like it went missing. My problem (I thought) was that I had no spark at cranking speed on at least one cylinder. This is from what I remember from last year. I did a spark test on all cylinders one at a time and started the motor each time on the other 3 cylinders. Each spark test was hot and consistent at 1/2" gap. I also used a timing light and each wire produced a consistent light pulse. The engine ran as good as expected on 3 cylinders with the wire off the test cylinder and no difference based on which 3 were hitting. Overall, the motor runs good. I'll watch it when I get it on the lake after it's run a while and keep the tester handy. It is the '77 model with one ignition module and 4 coils. Thanks for the input from my previous thread.

It seems like the folks running the site are getting the bugs worked out because it seems to be running better. Many thanks to the people that put this site up and to the many folks and experts that help out answering these threads.

Mark

 

[emdsapmgr]

You'll probably want to swap the "non-firing" coil with another on the engine. If you still have a no-fire situation on the original plugwire, then additional troubleshooting is in order. You will find some solid ignition troubleshooting info at this website: cdielectronics.com. I'd perform their suggested testing on the stator and the timer base. Their guide will show required minimum output voltages for both of these devices, perhaps min 150 volts from the stator at cranking rpm's and perhaps .03 volts at cranking rpm's from the timer base. Both measured with a special "peak-reading" voltmeter. (rent at a local auto parts store.) Check the website for the exact voltages for your 77. If they both qualify as good, then it's likely the power pack. All these ignition components are pricey, so some time spent troubleshooting will save you $ in the long run.

 

[MaPaHa]

emdsapmgr,
Thanks for the help. I've got an 85 hp evinrude "parts motor" with the same ignition system so I think I'll take off a coil or two and the power pack and toss them in the glove box along with the spark tester in case I have anymore trouble. Right now it's running great and firing hard on all 4 but thats on a set of muffs. What it does after it runs a while... who knows. I'll do the test on the stator and the timer base to see what those test at. If they test good and I have trouble later after running, it would seem to indicate something is breaking down under heat.

 

[emdsapmgr]

Good call.