18hp Johnson Seahorse 1960s White smoke and full choke

cosborn

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Oct 5, 2019
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Hello :). Wondering if anyone can give me some advice on a recently purchased Johnson outboard that’s all of a sudden having a number of issues... hoping that they’re all connected to one thing.

Motor ran great, besides occasional misfires. Idled very nice, makes my 14ft V hull fly.

Took it out yesterday and it was PAIN to start. A LOT of squeezing the bulb and full choke before I finally got it going, pulled so many times each time I needed to start it that I’ve got broken blisters between my fingers. It will only run at full choke and die if I push it in at all. Lean/low were the same as I had them before, kept giving it a little more to see if that would help, up to the point where it was starting to flood and backed it off again, but still couldn’t unchoke it without it dying. Won’t idle nice and low like it would before, have to keep a higher throttle. A lot of white smoke starts to show up from all over after getting underway. Appears to have a good pee stream still.

I’ve read that it may need to have the head gaskets changed, that white smoke usually means that water is getting into the cylinders, but would that have anything to do with the choke issue, difficulty in starting, and not idling too? (I sure hope so).

I also notice that it stinks the whole garage up with the smell of gas and leaks a black gassy discharge onto the floor. Small puddle.

Thank you.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Pull the flywheel and fix the ignition and it will burn that gas you are dumping into the cylinders and the excess smoke problem will go away. Most likely has bad coils unless they have already been replaced.
 

54bobby

Petty Officer 2nd Class
Joined
Dec 12, 2010
Messages
181
Hello :). Wondering if anyone can give me some advice on a recently purchased Johnson outboard that’s all of a sudden having a number of issues... hoping that they’re all connected to one thing.

Motor ran great, besides occasional misfires. Idled very nice, makes my 14ft V hull fly.

Took it out yesterday and it was PAIN to start. A LOT of squeezing the bulb and full choke before I finally got it going, pulled so many times each time I needed to start it that I’ve got broken blisters between my fingers. It will only run at full choke and die if I push it in at all. Lean/low were the same as I had them before, kept giving it a little more to see if that would help, up to the point where it was starting to flood and backed it off again, but still couldn’t unchoke it without it dying. Won’t idle nice and low like it would before, have to keep a higher throttle. A lot of white smoke starts to show up from all over after getting underway. Appears to have a good pee stream still.

I’ve read that it may need to have the head gaskets changed, that white smoke usually means that water is getting into the cylinders, but would that have anything to do with the choke issue, difficulty in starting, and not idling too? (I sure hope so).

I also notice that it stinks the whole garage up with the smell of gas and leaks a black gassy discharge onto the floor. Small puddle.

Thank you.

if water in the cylinder, plug would look nice and shinny clean from being boiled so to speak, not a healthy grey color, may have sheared the flywheel key, as fuel / air mix is controlled by timing via the cam plate and follower controlling the butterfly/ throttle plate in the carb which if any of those is off, would explain you having to manually control the fuel/air mix with the choke. wow that was tuff on a saturday morning. please , you guys that are more knowledgeable jump in here. i would start with the linc and sync setting before pulling the fly wheel to check the key. jm2cents.
P.S. if it's water in the cylinder, probably getting in through the exhaust cover plate due to aa breach from corrosion.
 

cosborn

Recruit
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Oct 5, 2019
Messages
5
Thing that really sucks is that the guy I bought this from had taken it in to professionals for a check-up, and it got a clean bill of health only to have this happen only the 4th time I had it out.
 

racerone

Supreme Mariner
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Dec 28, 2013
Messages
38,898
Weak spark is the main reason for hard to start condition and the " popeye " arms.------Does spark jump a gap of 5/16" on both leads , yes or no ?----Are you mixing gas and oil at 50:1 if newer than 1962 ?----Model # is ?
 

cosborn

Recruit
Joined
Oct 5, 2019
Messages
5
Weak spark is the main reason for hard to start condition and the " popeye " arms.------Does spark jump a gap of 5/16" on both leads , yes or no ?----Are you mixing gas and oil at 50:1 if newer than 1962 ?----Model # is ?

Yes, I am seeing sparks on both leads. Probably should get a tool to confirm the gap is 5/16", But the spark plugs appear to be new, and the leads don't look crimped in or anything.

Gas is a 50:1 muxture.

Model number is FD-17M. Looked that up and it's a 1963 model.
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,898
Correct-----Put the ignition system to a test to see if it can produce full output.-----Spark will jump a gap of 5/16" if the magneto is working as designed !
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Bad (cracked) coils are notorious for fooling the best of us. They can produce a spark, but not run. Been there, seen that too many times to count.
 

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F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
By the way, never pull a Johnson motor so many times that you hurt yourself. If it isn't running by 4 or 5 pulls, there is something wrong with it or the operator. Stop pulling and figure out what the problem is.
 

cosborn

Recruit
Joined
Oct 5, 2019
Messages
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Just ran some tests after getting some new tools.

All compression tests captured 100 psi from both cylinders consistently.

For the spark tests I used an adjustable tool, so I could vary the distance and see how long of a spark could be generated. I heard this was a lot better then some of the light or don’t light ones that may not detect a weak spark, lighting up anyway.

One line can consistently generate a 1cm spark, straight line, which looked bright white to me. I assume this is the bright blue/purple the test indicates as normal... my eyes just can’t detect that subtlety with something that is there and gone that quick while being shaken due to me yanking in the starter.

The other line didn’t so hot. 1/2cm spark was its max, was whitish fading to orangish across the arc. Assuming this is the red that the instructions say means a bad coil.

Sounds like I’m taking off the flywheel?
 

54bobby

Petty Officer 2nd Class
Joined
Dec 12, 2010
Messages
181
Just ran some tests after getting some new tools.

All compression tests captured 100 psi from both cylinders consistently.

For the spark tests I used an adjustable tool, so I could vary the distance and see how long of a spark could be generated. I heard this was a lot better then some of the light or don’t light ones that may not detect a weak spark, lighting up anyway.

One line can consistently generate a 1cm spark, straight line, which looked bright white to me. I assume this is the bright blue/purple the test indicates as normal... my eyes just can’t detect that subtlety with something that is there and gone that quick while being shaken due to me yanking in the starter.

The other line didn’t so hot. 1/2cm spark was its max, was whitish fading to orangish across the arc. Assuming this is the red that the instructions say means a bad coil.

Sounds like I’m taking off the flywheel?

before you pull the fly wheel, pull the boot back on the wire and check to see if the spring/clip is contacting the wire correctly and check for rust/corrosion.
 

Alex Novo

Cadet
Joined
Sep 22, 2019
Messages
25
Do it once, do it right. Remove flywheel, replace points and cap for Atom red electronic ignition, replace coils and wires, visually inspect everything, remove and rebuild carburetor, new gaskets, fuel pump, filter, hoses, prime bulb, spark plugs properly gaped and since you already with all the tools out, change the impeller. Fresh fuel and the right oil mix (some older motors use 24:1 mix ratio. Brother I know very well about the cost and avoid frustration.
 

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cosborn

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Oct 5, 2019
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Update on the motor.

Been posting and getting advice from the fine gentlemen over at the Tin Boats forum.

I’ve replaced both coils, condensers, and one set of points. Cleaned the carb and replaced all gaskets. She is up and running even better than when I got her (little bit of backfiring before... none at the moment anymore).

Thank you all for the advice. I’ve learned a ton from this and feel like I know my motor (and motors in general) a lot better now.
 
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