1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

[digger658]

Always had a idling issue with this motor. Rebuilt carbs, checked all fuel lines (replaced most), checked gas tank, new plugs set at .30" Set the timing according to Jim Reeves WOT procedures and took it to the river. Ran better for about 20 minutes then the same thing....wouldn't idling in gear.

Did a spark test. Set tester at 7/16" gap and cranked it over. Top cylinder had no spark jump at all. Bottom cylinder had very eradic light blue spark. Adjusted tester down to 1/4" and couldn't see a spark on top and had a good regular spark on the bottom.

Wasn't until I got the tester down to 1/8" was there any spark on the top. I also notice that the seal coating on the back of the top coil had melted a few drops off the back and the bottom coil coating had what looks like bubbles.

Do you think these coils are breaking down from heat and causing the idling problem? Runs great at WOT.

Thanks

 

[Daviet]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

Yes, weak or no spark will cause idling problems. I would replace the coils if they are starting to melt the coating.

 

[digger658]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

Is there anything else I should look at or order?

Thanks

 

[boobie]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

Try the coils first and see what happens as long as there're melting.

 

[digger658]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

boobie,

replaced both coils and now I have a hot blue spark that jumps 7/16" on both cylinders. The problem I have now is every 3 or 4 seconds it backfires (out the prop) while idling. When it backfires, idling drops way down and then recovers, then backfires again in a cycle. Pulled the plugs and both are wet.

 

[boobie]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

Check your compression and see what you have.

 

[digger658]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

Had it checked last year and this spring.......Right at 130psi both cylinders both times. That is the only reason I keep mess'n with this thing is because of the good compression. Could I possibly pull the plug wires while running to see which cylinder is missing without damage to the coils?

 

[boobie]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

Yes. That's known as a cyl drop test.

 

[digger658]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

boobie/DavieT,

Once I isolate the cylinder with backfire do I look at electrical side or fuel side (carb) or both? Both spark plugs are equally wet so I'm thinking the carbs MAY be OK.

On the electrical side what would I look for or do?

THANK YOU VERY MUCH FOR YOUR HELP.

 

[boobie]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

Do the test and get back to us with what you find.

 

[digger658]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

Boobie,

When I pull the bottom plug wire the motor will run on one cylinder with not backfire. When I pull the top plug wire the motor shakes worst and within 1 second dies but still seems to be getting a hot spark. Took a spray bottom with 50:1 gas and sprayed in bottom carb while running. Motor smoothed out with no backfire but ran at a little higher rpms which is understandable. Looks like to me I need to pull the bottom carb and take a closer look see, you agree?

Also, noticed the rectifier was hot.....couldn't keep my fingers on it after about 5 second. This normal?

Thanks again.

 

[digger658]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

Went on and pulled the bottom carb and now soaking in Berrymans overnight. Still concerned with rectifier getting that hot.

 

[Daviet]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

Did you remove the core plug on top of the carb to clean the tiny passages in there?

 

[digger658]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

No but will tomorrow and resoak.......any trick to get it out?

 

[Daviet]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

Couple of ways, use a 1/8" drill bit and drill a hole in it and then pop it out with a scribe. The way I do it, just use an 1/8" punch and drive it through the middle of the core plug and pop it out. Which ever way you do it, DO NOT go any deeper than needed to go through the plug, don't want to damage the carb body. No need to resoak it, when you see the passages in the bottom it will be easy to clean them, I use a set of welding tip files to make sure they are clean.

 

[boobie]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

Are all the battery cable connections clean and tight on both the battery and the mtr ?? Red wire to solenoid tight ??

 

[digger658]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

Daviet, Got the plug, passages looked good, and put a new plug in.

Boobie, checked all the connection and looks good a tight.

Put carb back on and fired it up. Same thing, backfire and recover. Sprayed 50:1 in bottom carb and smoothed out. I'm not sure what else I could do to the carb. Float adjusted level with bowl and all passages clean.

Power pack maybe?

The one thing I haven't done is start the motor in the dark and check for spark jump. Don't think I'll find anything but will try tonight.

 

[digger658]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

Well, I just said heck with it and took it to a mechanic. He got it idling but it's a very rough idle. Motor jerks back and forth quite a bit. He said they lightened the fly wheel by 3 pounds and because of that these motors never ran as smooth as the older ones.

Overall i'm pleased that I can at least troll with the the boat now. But, I feel it could do better.

My question is if you have a intermitten spark on one cylinder, what and how would I trouble shoot it? I did change both coils.

 

[dockrat100]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

What did the mechanic do to fix it?

 

[digger658]

Re: 1986 Evinrude E40ELCDE 40hp. Will weak spark cause idling isses?

He said it was a leaking/pinched fuel line. This line went to the primer on the side of the motor. Don't know how this could affect idling.