95 johnson won't start cold

mjbrinks

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Jun 21, 2011
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Hey guys,
I have a 95 Johnson 50 hp that has a problem start when temps are below 40 degrees. It seems to run on just 1 cylinder, then after it runs(stutters) awhile and warms, it will go on 2 cylinders. I have had it not start at all when cold, like it isn't getting spark. Then get home and heat up my plugs QL78YC with a torch, put them in and it fires right up. Am tempted to line the inside of my motor cover with some heat tape to keep warm. In the summer it runs just fine. Is there a different plug that will tolerate colder temps?
 

racerone

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Start with some simple testing.-------Test the compression.------Test to see if spark will jump a gap of 7/16" or more.------Test and see if the injection primer is squirting fuel into the engine.------Test the primer while cranking the motor over with the key pushed in.------Heating blankets should not be needed at all !!
 

gm280

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Jun 26, 2011
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I am assuming it is a single carb engine. Have you tried spraying some additional fuel/oil mixture into the card when cold to see if that helps? Also, if you suspect the plugs are the issue, change them and see if that's it. Either way you will either find out the plugs are the problem, or end up with a addition set. And extra plus are never a bad idea to have around... JMHO!
 

mjbrinks

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Jun 21, 2011
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Thanks guys for responses, As stated everything as runs good in the summer. Just when starting cold in the morning in the spring. It will even flood out if i don't catch it in time. Like there is no spark or lack of. Do you know of a different plug say Champion QL77JC4
Or NGK's
 

boobie

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Did you check the injection primer ?? It takes more fuel to start a cold motor.
 
Last edited:

mjbrinks

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It will even flood out if i don't catch it in time. Like there is no spark or lack of. Do you know of a different plug say Champion QL77JC4
Or NGK's
 

Bosunsmate

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Use a spark checker to check whether no spark and if so which cylinder no spark.
 

gm280

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Want Bosunsmate suggested. When it is cold, like everywhere it seems now, try each plug out of its cylinder so you can actually see the spark. Verify every plug is firing when cold. If no, you have found your problem being the ignition system... Then you can isolate coils or whatever you have from there. Also if you do have a plug not firing, swap in a known good plug to see if it was the plug or the ignition. JMHO!
 

boobie

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Good thought by GM280. Check your spark when cold. Should jump a 7/16" open air gap on a tester. Electrical components can contract when cold and you may have an open circuit in one.
 

Faztbullet

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From what you posted it appears to be a fuel problem instead of a ignition issue. The reason why is that heating plugs with torch will increase resistance in plug which would likely cause a lesser spark if it is already weak but, it will dry out a fuel fouled plug. I would check the primer and carb to see it they a leaking/flooding since you stated it easy to flood out. Also a fouled plug will cause a miss till it cleans itself or cylinder.
 

mjbrinks

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I'm liking your input fazbullet..... do you think an NGK plug will spark better in a to much fuel situation. " Champion QL77JC4
Or NGK's" am currently using QL78YC
 

jakedaawg

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Both plugs are essentially the same. Properly diagnose and address the issue. Just because it runs goos in the summer does not mean you don't have a compression issue. Summer and winter fuels are different. Winter fuels are more readily atomized at low temps.

Run a compression test. No point in going further without doing a 2 minute check.
 

jakedaawg

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That brings to mind another thought. When did you last put gas in the tank you use to fill the boat? Does it still have gas from last August in it?
 

mjbrinks

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OK It is the middle of winter in Michigan.......am prepping for spring. Am not going to do testing.
Champion QL77JC4 SAME?
QL78YC SAME?
NGK equivalent SAME?
 

mjbrinks

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The very first question I asked was about plugs. Is there another plug other than the QL78YC that is recommended for a 1995 johnson 50hp, that anyone has had luck with. say QL77JC4 or an NGK?
 
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