9.9 Johnson Sparks on one cyl only

[riddert]

Hoping you guys can confirm my guess of a bad powerpack on this engine before I go out and buy one...

1983 9.9 Johnson I just bought. Sparking on top cyl only so I switched the orange wires coming from the powerpack to the coils. Low and behold the bottom coil fired up while the top coil lost spark. This tells me that both coils are good, and that one of the two orange wires coming from the powerpack isn't sending voltage.

Considering there is only one charge coil in the stator and only one trigger AND I am getting spark (albeit on one cylinder) then they must be functioning correctly. Am I using good logic here?

If the above is true, then this only leaves me with the powerpack as the problem. Have you guys ever seen a powerpack go bad only on one cylinder? I have checked all my wires, gounds and connections so hopefully have ruled out a short.

Thanks!

 

[tashasdaddy]

Re: 9.9 Johnson Sparks on one cyl only

you are on the right track.

 

[jay mendoza]

Re: 9.9 Johnson Sparks on one cyl only

Power packs on the 9.9/15 engines are notorious for going bad. Some claim extended low speed operation overheats them? I'm not sure what goes bad, but I have replaced my share of them. They tend to become intermittant when heated up, as several I had worked well when cold, but started to act up as the engine got hot.

 

[riddert]

Re: 9.9 Johnson Sparks on one cyl only

That would make sense. This little motor was used mostly on low speed for trolling. Have you ever seen the powerpacks go bad only on one cylinder? I may have been misinformed, but was told that when they go bad you will get no spark on either cylinder. Is this correct or incorrect? Basically I just need to make sure I have this narrowed down to the right component to replace. Would hate to buy a new powerpack and find out there was something else wrong.

Also, just did a compression test and I am getting about 90psi on both. That seems low. Was hoping for 110 to 120. Will I get full rpms at 90?

Oh...one more thing. Previous owner told me he thinks it has a 15hp carb on it. What is the best way to confirm this? I will be cleaning carb later today for a closer look. Could this carb cause me any issues? Does it really get the engine up to 15hp?

 

["G"]

Re: 9.9 Johnson Sparks on one cyl only

The difference in the 7.5 and 9.9 Mercs was all carburetor. In these later model Johnson's I'd suspect the same. However that's a jet thing not a difference in carb kits per se'. The gasket sets will most likely be the same.

As for the ignition problem... good DX skills switching coils/wires. Yes, you are correct, if the power pack goes south you get no spark at all.
That said, I don't think this is a power pack issue. Heres' why... power packs only magnify the power from the "magneto" (in this case the electronic magneto- aka stator). The trigger is the electronic part that replaces points and it "tells" the ignition system which coil to energize. I'd make bets your trigger is bad not the power pack. Further, the stator makes power off the rotation of the flywheel. If it were bad it too would not produce spark. See where you've done your DX skills well?

In any case, under the flywheel is where I'd be looking, not the side of the engine. Your DX proves the power pack and stator are both working. Now... is any of that integrated? That's another question. Still under the flywheel is where I'd look.

I don't think the compression is that bad either. Remember that old engines won't be popping out "new engine" compression readings.

Good luck!!

That would make sense. This little motor was used mostly on low speed for trolling. Have you ever seen the powerpacks go bad only on one cylinder? I may have been misinformed, but was told that when they go bad you will get no spark on either cylinder. Is this correct or incorrect? Basically I just need to make sure I have this narrowed down to the right component to replace. Would hate to buy a new powerpack and find out there was something else wrong.

Also, just did a compression test and I am getting about 90psi on both. That seems low. Was hoping for 110 to 120. Will I get full rpms at 90?

Oh...one more thing. Previous owner told me he thinks it has a 15hp carb on it. What is the best way to confirm this? I will be cleaning carb later today for a closer look. Could this carb cause me any issues? Does it really get the engine up to 15hp?

 

[jay mendoza]

Re: 9.9 Johnson Sparks on one cyl only

Your coils are good, as you were able to get them both working, but one output from the power pack is bad. This is a common problem on 9.9/15 Johnsons and Rudes. Others have had good spark on one cylinder, and a weaker spark on the other, the engine ran, but poorly. Replacing the power pack cured this.

The carb bore size is slightly bigger on a 15hp carb, but externally they appear identical as they are both made from the same casting. However, the gasket between the carb and intake manifold has a hole that perfectly matches the diameter of the carb bore if it's a 15hp carb. If it's a 9.9hp carb, the hole in the gasket is slightly larger than the carb bore. You must compare the carb bore where it mates to the gasket to check this, meaning you have to remove the carb.

Compression tests vary, but one thing above all is that both cylinders read within 5% of each other, this is important. Opening the throttle will raise the reading slightly, a warm engine gives higher readings, squirting oil in the cylinders raises the readings. Rings stuck with carbon will give lower readings, as will a cold engine.

I always check my engines cold, as it's hard to get them exactly the same temperature every time when doing a warm check. 90 to 125 PSI is good, most guys like to see 110 PSI or better. I have a 1975 9.9 that has run for 27 seasons with 97 PSI on #1, 92 PSI on #2.
The main thing to look for is a big differance between cylinders, or a sudden loss or drop off of compression as compared with previous readings.

 

["G"]

Re: 9.9 Johnson Sparks on one cyl only

Jay-
Your suggestion on one part of the power pack being bad could be the problem if Johnson outboards split their power packs. Sounds like you have had experience with them. Can't say I've ever come across this problem.

So for my benefit; is there no trigger under the flywheel on these? I find it interesting how manufacturers will change how ignition is routed. It all helps with finding issues on the next one.

"G"

 

[riddert]

Re: 9.9 Johnson Sparks on one cyl only

Yes, one of the two orange wires coming from the CDI gives a strong spark on any coil it is hooked to while the other orange wire does nothing on either coil. That is why I assumed the trigger was working since it is designed to fire both coils. Same with the magneto...one unit operates for both coils. If trigger or mag was bad I didn't think I would get any spark at all.

Well, I guess I need to buy the CDI. I am reasonably certain now that is the problem. I was hoping it would have been one of the less expensive parts like a coil or trigger. Oh well...gotta have it.

Any thoughts on brands? Mallory, Sierra, OEM etc?

My compression tests were done cold as well. I did spray a bit of WD40 in spark plug holes hoping it would help seal rings a bit. I suppose, though, that after sitting for six years I might have some sticky carbon in my joints too. Maybe after I get it up and running it will come up a bit. This little engine is very sweet and doesn't look like it has been used much. Looks no worse for wear than one that is five or six years old.

As for the carb...I did take it off and clean it out. Good thing too - it was really quite mucked up. I took my time with it and wired out all the orifices and used compressed air. Should be good to go.

The carb mounting gasket matched the carb bore parfectly. Carb also has a part number stamped on a small aluminum tab that attached under the fuel bowl. I looked it up and it came up as a 15hp carb.

Big question is will I really get 15 HP out of it? Can't wait to try it out!

 

[jay mendoza]

Re: 9.9 Johnson Sparks on one cyl only

The bigger carb gives more power, exactly how much depends on the condition of your engine, and if someone added the other 15hp parts, but the carb is the single biggest improvement, so the long and short of it is"yes".

Check the power pack mounting screws, are they loose? We have seen blue sparks jumping from a power pack to the engine that had loose mounting screws, presumably it was not properly grounded due to the loose screws. Anyway, we tightened the screws but the damage had been done and it continued to not fire on one cylinder. We swapped the orange wires and then the problem moved to the other cylinder, so the coils were OK. Changing the power pack cured this problem.

There is a trigger/pulsar coil under the flywheel on these models.

 

[riddert]

Re: 9.9 Johnson Sparks on one cyl only

The bigger carb gives more power, exactly how much depends on the condition of your engine, and if someone added the other 15hp parts, but the carb is the single biggest improvement, so the long and short of it is"yes".

Check the power pack mounting screws, are they loose? We have seen blue sparks jumping from a power pack to the engine that had loose mounting screws, presumably it was not properly grounded due to the loose screws. Anyway, we tightened the screws but the damage had been done and it continued to not fire on one cylinder. We swapped the orange wires and then the problem moved to the other cylinder, so the coils were OK. Changing the power pack cured this problem.

There is a trigger/pulsar coil under the flywheel on these models.

Jay, what other parts are there to add for a 15hp conversion? I need to check and see if I have them too.

 

[bktheking]

Re: 9.9 Johnson Sparks on one cyl only

http://www.sschapterpsa.com/ramblings/Johnson 9.9_15.htm

Read the 9.9 and 15 differences section

 

[riddert]

Re: 9.9 Johnson Sparks on one cyl only

Thanks to everyone who chipped in to lend me a hand. It is very much appreciated! We are lucky to have a board like this and to have such knowledgeable people willing to give out their expertise and experience!

Good news too! The new powerpack did the trick! A couple of pulls later the engine was humming along perfectly! Such a nice little motor and so quiet too!

I checked the compression after it ran for 10 minutes or so and it came up to 110 on both. Guess I am in business. Taking it out on the lake tomorrow for a test run.

Again...thanks to everyone!

 

[bktheking]

Re: 9.9 Johnson Sparks on one cyl only

It's usually the powerpack, weakest part of the system, too bad they aren't cheap!