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1973 Johnson 50hp being difficult

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billythegrape

Regular Contributor
1973 Johnson 50hp on a 24' pontoon boat.

Well, after replacing the gas cap on my engine in this thread: http://www.marineengine.com/boat-fo...1973-Johnson-50hp-suddenly-hard-to-cold-start , I was golden for a while. For reference, I use this boat every weekend, usually with 2-3 6 gallon tanks going through it.

Suddenly, the controls got wonky. The engine wouldn't start because it wasn't resting on the neutral button. Also, the warmup lever wasn't doing anything at all. I adjusted both and got it working again. Maybe the cables stretched? who knows.

My problem now is two fold. The motor is running ok, but not as well as it should be. It's almost as if something is holding it back, because every now and again it will stutter, run at a higher, more "proper" RPM, and travel as fast as it should (which granted isn't very fast). The plugs are black, chunky, and wet, which obviously indicates richness.

Secondly, it has become hard to start again. It will catch and die over and over again. If I choke it, it is worse, indicating richness. Starts just fine in the driveway. To get it going in the water, I have to raise the warmup lever to its utmost position to get it to stay running. Generally I will run it about 5 miles out to an island, park all day, then go back. It has no problems after the initial start up at the boat ramp.

New parts, time of replacement:

Rebuilt the carbs with Johnson kits- last season
Johnson coil packs- May
Johnson fuel pump- May
copper plugs- August
fuel filter- May
foot oil- May
prop- last season

Fuel is generally 91 octane 100% gasoline w/50:1 mix. Sometimes I use 87 octane 100%, but not too often, and it doesn't correlate with running issues. It doesn't smoke excessively or anything like that. I started the carbs at 5/8 of a turn out and brought them in until the engine ran smoothly, maybe an 1/8 of a turn each if that. The plastic access caps for the needles are missing from the carb housing. Engine has a decent pee stream.

What else should I check? The flywheel has some kind of brown crap that leaked from underneath it, but it looks old. Is there an ignitor under there I should worry about? What about ignition timing? Is this adjustable? How would one check it? Should I throw my gas tank out and get a new one? Should I light the boat on fire and give it a Viking funeral? HELP!!!
 
Have you looked at the thermostat , yes or no ?------Replaced the water pump impeller , yes or no ?-----Yes there are coils under the flywheel that have to do with getting spark and to charge the battery.-----Best to remove the flywheel to have look under there.
 
Have you looked at the thermostat? No, I have not.

Replaced the water pump impeller? No, I have not. However, If it has a healthy pee stream, then shouldn't the impeller be ok?

Yes there are coils under the flywheel that have to do with getting spark and to charge the battery. Best to remove the flywheel to have look under there. Ok, will do and reply back. Is it reverse thread?
 
No the thread on the crankshaft in NOT a left hand thread.-----You need to use a puller with 3 bolts ( 5/16" fine thread ) to remove the flywheel.
 
Whether the stator is your problem or not is up in the air as no pictures come thru, nor is there any exact description of the stator that I came across........

However... if that stator is dripping a sticky looking substance down on the timer-base and powerhead area, that would result in a AC voltage drop to the powerpack's capacitor. In which case it requires replacing.

In that state, when cold and at the beginning of its failure, it might function like a new one... BUT... within a short time the ignition/spark would become weak, erratic, and eventually there would be NO ignition at all... especially when warm.

Whether the stator is your only issue remains to be seen... BUT... it's one of them. Replace it.
 
joereeves said:
Whether the stator is your problem or not is up in the air as no pictures come thru, nor is there any exact description of the stator that I came across........

However... if that stator is dripping a sticky looking substance down on the timer-base and powerhead area, that would result in a AC voltage drop to the powerpack's capacitor. In which case it requires replacing

In that state, when cold and at the beginning of its failure, it might function like a new one... BUT... within a short time the ignition/spark would become weak, erratic, and eventually there would be NO ignition at all... especially when warm.

Whether the stator is your only issue remains to be seen... BUT... it's one of them. Replace it.
Click to expand...

The stator is for sure leaking on to the power head. When it acts up is when the engine is cold, just the opposite of what you said. However, it isn't running great, so I guess that'll be the next part on the docket.

Pics are in link form 3 posts up.
 
I see the pictures. The black coils are the ones that charge the ignition system, and they are leaking. If they aren't giving a problem yet, they will soon. Time fpr a new stator.
 
fdrgator said:
I see the pictures. The black coils are the ones that charge the ignition system, and they are leaking. If they aren't giving a problem yet, they will soon. Time fpr a new stator.
Click to expand...
Ya thinking this is what's causing my running problems from the first post. Expensive as hell though
 
The part has done its job faithfully ( I assume ) without maintenance costs for some 45 years.----Why say " expensive " in this case ??
 
I say expensive because $150 is expensive. I'm not rich, which is why I'm rocking a 24' ****box with a 45yo motor. You are correct, though, it does appear to be original, which is a helluva long time to work.

Yes, the definition of BOAT fits here very well, haha!

Question for you guys: do you trust CDI for parts?
 
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