1990 Johnson 88 SPL starting/running issues

Joined
Jul 5, 2015
Messages
8
I recently purchased a lund with the stated motor on it. I have been having some issues with it. The motor had the plastic carb bowls which I removed and replaced with the new aluminum ones. While they were out I cleaned and rebuilt the carbs. This solved the problem of gas leaking out of the bowls but didn't fix other issues.

Problem: 1. the engine is a little tough to start, I have to move the throttle to a pretty high idle while bumping the enrichment on the key to fire the engine and slowly move it back to a reasonable high idle. Once it is warmed up I have to keep bumping the enrichment for it to go into neutral and then into gear. This is about a 10 min process to keep it running. It stumbles a little in gear at low rpms but is solved by the enrichment button. Once it gets to a higher rpm it runs like a champ and will idle just fine. If I turn the key off it'll fire back up without issue.

2. if I stop to fish for maybe 45 min I need to do the whole process over again, I can't just turn the key on a warmed up engine and go.

Any suggestions on what to do? I noticed when the carbs were off the sleeve on the throttle roller has fallen apart so I have one on order. I am getting a manual from my local library to look up the link and sync process. I am also going to borrow a compression gauge to check compression. Any other suggestions, do I need to try to clean the carbs again? Does it sound like a compression issue?
 

racerone

Supreme Mariner
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Dec 28, 2013
Messages
36,287
These motors are known to have compression / piston ring issues.
 
Joined
Jul 5, 2015
Messages
8
If it is a piston ring/compression issue would a decarb be something that could solve the issue or is it a for sure rebuild at that point?
 
Joined
Jul 5, 2015
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Compression numbers were 115psi on 3 of 4 and 95 psi on the fourth. Is this enough for a rebuild? The engine runs really well when it's warm, idles and performs well. Just the first startup and when it's been sitting for about 45 min, then it becomes an issue.
 

Bosunsmate

Admiral
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Apr 7, 2012
Messages
6,129
After 45 min the engine will be cold again. Id check that your thermostats not stuck open
 

racerone

Supreme Mariner
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Dec 28, 2013
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36,287
Remove bypass cover on the side of the lowest compression cylinder.-----Just 6 small bolts ..------Have a look at the piston and rings.
 
Joined
Jul 5, 2015
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I pulled the cover off and was able to take a picture of the piston. It looks like I'm missing part of my upper piston ring. I suppose next I'll pull the head off and see if the cylinder or piston is damaged. Does this mean pulling off the powerhead or can this be replaced by just pulling off the head?


photo (1).JPG
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,287
Good work on following my suggestion.-----No there are no shortcuts to this job.--Powerhead should be pulled for this type of repair.------Remove the cylinder head and see if there is any damage to the cylinder.
 
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