Help with 115 Evinrude

[timapexcomputer]

Hey all Tim here.

I have an MX16 with a 1980 Evinrude 115 hp - E115TLCSA. Just did a new head because of a bad plug hold that was beyond repair. Also did carb kits and impeller.

Motor is running very, very well. So we go out, take a good run at 45-50mph GPS on a little 17p prop. Respectable in my eyes.

Anyway, after about 15 minutes it stops running good. Once hot I assume. It still goes but like it is an 80 HP instead of a 115. No sound difference but much lower RPM. Takes longer to plane too.

I feel like it is down a cylinder when hot.

So a bad coil is my assumption. Here is my question:

What would you do to figure out if it is a bad coil, and which one? Each of the 4cyl's has its own coil and because it only does it when hot, the plugs all read the same.

Thoughts? Any help is much appreciated. Cheers, Tim

 

[Will30]

Hey all Tim here.

I have an MX16 with a 1980 Evinrude 115 hp - E115TLCSA. Just did a new head because of a bad plug hold that was beyond repair. Also did carb kits and impeller.

Motor is running very, very well. So we go out, take a good run at 45-50mph GPS on a little 17p prop. Respectable in my eyes.

Anyway, after about 15 minutes it stops running good. Once hot I assume. It still goes but like it is an 80 HP instead of a 115. No sound difference but much lower RPM. Takes longer to plane too.

I feel like it is down a cylinder when hot.

So a bad coil is my assumption. Here is my question:

What would you do to figure out if it is a bad coil, and which one? Each of the 4cyl's has its own coil and because it only does it when hot, the plugs all read the same.

Thoughts? Any help is much appreciated. Cheers, Tim

Warm it up on the hose and do a compression check .

 

[timapexcomputer]

Sorry forgot to mention. Did compression test before and after the head swap, and again when this problem began.

Top Stb: 120
Bottom Stb: 120

Top Port: 117
Bottom Port: 116

Stb was the swapped head.

It has always been almost bang on the same. I have ruled out compression and fuel as the issue. It did this before carb kits, and took them off after that soaking them in carb clean and clearing all passages, etc etc etc.

I am sure it has to be a coil. I fear the only way to determine that is to buy one and start doing test runs with the new coil on each cylinder until it stops acting up.

 

[redstrat]

Spark tester will do the trick. http://www.wholesalemarine.com/spark-tester-by-cdi-4120.html

 

[atc250r]

Do you have a timing light? When it feels like a cylinder is down connect the pickup of the light to each spark plug wire until you find one that doesn't pulse the light or at least doesn't pulse it consistently.

 

[timapexcomputer]

Thanks all. I have a spark tester but it is single cylinder. I like the timing light idea too. So the plan is:

Run up and down the river with someone else driving. When it starts to act up:
1 - Shut it down
2 - Put spark tester on Cyl 1
3 - Run it and make sure cyl has spark
4 - Rinse and repeat for each cyl
5 - Once non-sparking cyl is found, replace coil

Sound right? I will do this with a spark tester because I do not have a timing light - but I could see how that would be much easier. I will try to borrow one to save the trouble of shutting down and switching the tester every time.

Wish me luck

 

[atc250r]

Sounds like a plan. You could swap the coil with to another cylinder and see if the problem follows the coil or stays on the same cylinder to narrow it down.


Pick up a cheap timing light at Sears or AutoZone. AutoZone might even have a loaner one.

 

[timapexcomputer]

Excellent. I am going to try to borrow one and if that fails, buy one. Unfortunately I do not know which cylinder is acting up so swapping coils around wont work.

 

[Jimway]

The next time you pass the auto parts store, stop in and look at the K-D or Lisle tool section. They used to market an inductive spark tool that you merely attach it's ground clip to a good ground and then place other end that looks kind of like a sharpie pen with a led light in it against the plug wire. pretty easy to see a weak or misfiring secondary ignition system with this little device. Think it was inexpensive too. Watch out for the flywheel and ring gear teeth while the motor is running.

 

[atc250r]

Unfortunately I do not know which cylinder is acting up so swapping coils around wont work.

I think you missed my point Tim. Once you determine which cylinder is not getting spark swap that coils position with one of the other 3 on the motor. If the lack of spark follows the coil it's a coil problem. If it continues to not fire on the same cylinder it's something else.

 

[timapexcomputer]

Hi. I think i did miss that point sorry. I bought another coil cause it was only $40 at a local marine place. I know - $40. What is going on? And it's OEM!

Anyway, test results are in. Was top starboard that would stop firing when hot. Timing light worked like a charm. However - I put the new coil on and it is still doing exactly the same as before. Fine cold - not fine hot.

Ran out of time to test but I will get on it again tomorrow.

What's next?

I was thinking I need to investigate the trigger wire (orange) that runs from the coil up to.. well, where ever it goes. Thoughts?

Thanks again everyone. I really appreciate the help.

 

[keith4216]

Swap plug and wire on that cylinder with a known good one.

 

[Bill Gohr]

Well you could test it with a Peak reading volt meter, that would tell you exactly what is wrong, otherwise you need a timerbase or a pack, call me if you want 847 356 3245

 

[timapexcomputer]

Thanks guys. Tonight I am going to install known to be good plug and wire on that cylinder. Go for another run and see what's what.

I will also investigate all wiring and make sure everything looks good. Its such an odd problem. It's like a light switch. The cylinder just shuts off. If you power down and idle for a few minutes, you can hear it turn back on. Has me baffled.

 

[Bill Gohr]

no need to be baffled it sounds like a pack. I had one that would drop a hole and you could just open the hood and tap on it with the stern light and it would come back

 

[timapexcomputer]

I think that is what is going on. Did new plug and wire and went for a rip. I left the timing light on that cyl and sat the light on the back seat facing forward.

After about ten minutes it would stop flashing with no warning. If I reduced to idle it would start again after a few minutes. Then on plane it would stop again.

Power pack? I checked with the marine folks and it is not that expensive so I am going to get a new one.

I also took this opportunity to put some new wire and connectors on all four coils just to be safe

I really appreciate all the help guys

 

[timapexcomputer]

Bah this boat is killing me.

New pack on it now. Now coil new wire and new plug. Top stb cylinder is still shutting off once it's hot.hot compression on that hole is 120. What do I try next?

Thanks again for everything guys.

 

[Jimway]

Just some thoughts here. What about the timer/trigger? You could check power to coil when motor heats up. Could be that the trigger or its wiring is causing this intermittent problem. Also make sure that the motor is well grounded and bonded. It does sound as if you have isolated the problem to the particular cylinder. If you lose the ignition event signal to the coil, check the signal coming from the timer/trigger. See if it goes away when hot.

 

[timapexcomputer]

Thanks for the advice. While I do not know what the timer/trigger is, I would imagine that if I follow the wires I will figure it out.

to test this, I check for current with a volt meter north of the power pack while the motor is hot... will try it tomorrow.

 

[Jimway]

Up underneath the flywheel is the stator and underneath it is the timer/trigger. I think Johnson/Evinrude calls it the timer. Does your motor have one power pack . The timer gets a signal from a magnet attached to the center of the flywheel as it rotates to cause the power pack to send a signal to the correct coil at the correct time to produce a spark. The stator is under there too and uses magnets attached to the outer underside of the flywheel to produce power for the ignition system and also for the charging system. These magnets can not be loose or cracked or missing pieces. look at the wires from the timer to make sure they have not become bare and are making contact to ground. The ignition system produces some pretty high voltage even at cranking speed, like 150 volts or more at the orange wires from the power pack while connected to the coils. What plugs are installed and what are they gapped at?