1976 Evinrude 9.9Hp Misfire

[catalyst-519]

Hey Guys:

Fired up a motor I just bought for the first time this w/e. Had it out on the water and the motor died and would restart. Felt like it was only running off 1 cyl.

Got it back home and assumed it may have been bad gas. Tested spark and found that top plug spark was very weak. Pulled plugs and found that top plug was completely fouled but bottom plug seemed in much better shape.

Replaced plugs and gas but now noticing a misfire when motor is in low idle. Motor will sometimes keep running but will mostly stall after this misfire. In order to get the motor to turn over again I need to squeeze the bulb as well.

I'm going to throw another set of plugs in as the kid at Canadian tire sold me the NGK equivalent plugs instead of the Champions that are listed. Could this be the problem perhaps?

What should I be looking for next? What is the difference between a misfire and a backfire and how would I know? I am assuming this is a misfire as the engine chugs, slows down and spits a lot of smoke after it happens. No loud bang more like a wheeze.

The old guy I bought it from said he tended to run the gas very rich. But he also said he had it out running earlier this spring and it ran just fine.

Any help would be greatly appreciated.


Cheers----519

 

[catalyst-519]

Re: 1976 Evinrude 9.9Hp Misfire

Forgot to mention that when I tested the spark and grounded the top lead to the motor I got a solid and strong blue spark. When I grounded the tester to the actual plug with it in the cylinder it produced a very faint red/pink spark. I'm assuming that this suggests a bad plug but then the issue should have been fixed by replacing the plugs.. . .right

I've been all over this site and it seems as if it could be many issues from the wires to a ground problem to the coils and points.

Even a link to a FAQ or tutorial would be extremely helpful.

thanks---519

 

[catalyst-519]

Re: 1976 Evinrude 9.9Hp Misfire

I am assuming that since there has been 0 response, this question has been answered before. A link would be great. Thanks guys.

Cheers----519

 

[CATransplant]

Re: 1976 Evinrude 9.9Hp Misfire

Sorry nobody jumped on your question. I'm assuming that you checked spark on both plugs....right?

You will get a weak spark if you test with the spark plug installed and the tester connected to the spark plug.

If you have strong spark from both wires, when connecting to the engine, then you can assume that part's OK for now.

You just got this outboard? So, you don't really know its history. From the symptoms, it could easily be a dirty carburetor. It could still be the ignition system, especially if it only acted up with the engine warm.

The trick here will be to run it in a barrel until it's warm, and then pull one plug wire at a time. If it dies when you pull one plug wire, but doesn't change when you pull the other, then it's an ignition problem.

If you follow the standard steps of checking compression, checking spark, and cleaning the carb, you'll probably have this engine running fine soon.

 

[iwombat]

Re: 1976 Evinrude 9.9Hp Misfire

If this is a new motor to you standard operations are.

1) New impeller/waterpump.

2) Carb rebuild.

3) Replace lower unit lube.

Those are kind of automatics unless the previous owner can produce receipts showing it done in the last year or so.

You'll save yourself a lot of grief and head-scratching with those three things.


Edit: Should have included new plugs too.

 

[catalyst-519]

Re: 1976 Evinrude 9.9Hp Misfire

Thanks for taking the time guys. I'll follow the steps below to determine the problem. I'm sure you'll hear back from me if I can't resolve the problem.

--519

 

[catalyst-519]

Re: 1976 Evinrude 9.9Hp Misfire

OK Guys:

The saga continues......

I've replaced the plugs and done a thorough decarb using the dual seafoam/fuel and deep creep method. I've also used the exact plugs listed by Evinrude Champion UL81C.

I've pull off all contacts and cleaned them with emery paper


This is what's happening.

The motor is continuing to misfire once up to operating temperature. I know that it's the top cylinder as the misfire ceases with the top plug disconnected, however the motor will still stall out after 30-60 seconds on 1 cyl.

When I test the sparks to ground they are both present and fairly strong. When I test the ignition wire to the bottom plug, the spark is strong. When I connect the tester between the top plug and the ignition wire, no spark is present what-so-ever.

I have searched this forum and have determined that it may be either a coil or powerpack issue, but ignition systems are a new bag for me.

I've yet to pull the flywheel, but will this motor have an additional set of coils under the flywheel in addition to the coils mounted on the side of the crankcase? (4 coils total) If so, how do you determine which coil is the culprit.

If not the coil how do I determine a powerpack issue?

I've taken a couple photo's and hoping someone could tell me what I'm looking at?.

Any comments on the next steps would be greatly appreciated.

CHeers-----519

 

[catalyst-519]

Re: 1976 Evinrude 9.9Hp Misfire

Also forgot to mention that the misfire does not appear to happen when in forward gear or at max idle, only in mid to low idle.

 

[catalyst-519]

1976 Evinrude 9.9Hp Electrical Troubles.

1976 Evinrude 9.9Hp Electrical Troubles.

Hopin for a response.

 

[OptsyEagle]

Re: 1976 Evinrude 9.9Hp Misfire

It sure sounds like a bad coil to me. Can you see any cracks in the plastic. Older coils can start to arc after they warm up causing problems like you are having, unfortuneately, apart from changing them to find out, I do not have any other method to test them (not for intermittent failure). I suppose you could change the boots to the cylinders and see if you now are having a problem with the other cylinder, but that still will not guarantee that it is the coil (could be the points but if they were to fail it would usually be irregardless of the temperature of the motor).

Just so that you know, you do not have a powerpack on that motor.

My best guess is the coil but it is just a guess. I am not a certified mechanic but more a certified boater who seems to have a lot of problems with his motors and thankfully a lot of help from the people on this site. If you were going to change the coil, I would probably do them both. Good luck.

 

[catalyst-519]

Re: 1976 Evinrude 9.9Hp Misfire

Thanks, I have a feeling that the top coil is original and the bottom has been replaced. No cracking, but the top coil is coated in a green film that I believe came on the original Evinrude coils. I'll replace it and see what happens from there.

If I have no powerpack what am I looking at in the pic entitles "whatsthis". There are a bank of wires coming from the magneto and going to the coils. Also looks like they're going into some kind of solenoid. Any thoughts?

Thanks Optsy.

 

[Xcusme]

Re: 1976 Evinrude 9.9Hp Misfire

If I have no powerpack what am I looking at in the pic entitles "whatsthis". There are a bank of wires coming from the magneto and going to the coils. Also looks like they're going into some kind of solenoid. Any thoughts?

Thanks Optsy.

Looks like the terminal strip and the rectifier....

 

[OptsyEagle]

Re: 1976 Evinrude 9.9Hp Misfire

I think you are right on the coil difference. In that case, I would just change the top coil. They inevitably degrade and I am about 90% confident, that you have a coil problem. Good luck.

 

[bmw-razze]

Re: 1976 Evinrude 9.9Hp Misfire

hello. I know this is long time ago, but i have the same problem with my engine right now. Did the new coils make any result...

 

[Xcusme]

Re: 1976 Evinrude 9.9Hp Misfire

Welcome to iboats !
You will receive a greater amount of responses by posting your question in a new post , (the other posters would rather ignore your request)

I'm sure someone would be happy to assist you, and again Welcome !!

 

[OptsyEagle]

Re: 1976 Evinrude 9.9Hp Misfire

Yeah, start a new thread. You will find that a lot of posters only come back when their motors are still broken and could not be bothered to return once their problem gets resolved. That in itself doesn't mean that the suggestions offered here were the fix, just that once their problem was resolved, however they resolved it, they didn't really care to help others by completing the thread with whatever the final outcome was

Luckily there are quite a few exceptions to this, but I wouldn't hold your breath. Start a new thread for yourself.

 

[WIMUSKY]

Re: 1976 Evinrude 9.9Hp Misfire

hello. I know this is long time ago, but i have the same problem with my engine right now. Did the new coils make any result...

Welcome to the forum. You may want to familiarize yourself with the forum rules...

http://forums.iboats.com/forum-rules-guidelines/forum-rules-397820.html

12. Please do not post to threads that have been inactive for more than 3 months UN-LESS you are the original poster. We have very active forums and any thread that remains inactive for that long should be considered "dead". It is especially confusing when there is an entirely new question posted to an old thread. This is considered a hijack. Please start a new thread of your own.