1976 Johnson 85 hp idling issue again need help

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tom5410

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Jun 14, 2010
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I have a 76 85 hp Johnson outboard 85EL76D that has me at my wits end, motor ran great 2 months ago, idle great after carb kit put in. Started up no problem, last week was going to take it to the lake but decided to start it on muffs first, as soon as I got it running with advanced spark I could hear the miss in it, slowed the rpm down and started popping through the propeller with some white smoke coming out and would die at low rpm. Found 2 ignition coils with cracks in them and the other two looked a little melted so replaced all four, set timing still no change. I have replaced power pack, timer base and sensor coil 2 months ago from no spark, put another carb kit in yesterday still no change, motor had good compression on all cylinder 2 months ago, I also put in new plugs, I have been checking spark, wires for bare spots, ground and still can't figure it out. Any help on were to go next on the popping would be greatly appreciated. Thanks
 
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EchoNovember

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Dumb question, when you did the carbs did you put the adjustment needles and screws back in exactly the same turns they came out? If not, the carbs need adjusting and tuning to get the fuel mixture right.
 
oldboat1

oldboat1

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Any overheating? Check compression again, using the numbers from 2 mos. ago as a baseline.
 
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tom5410

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yes the needles were all the way in. no overheating, haven't really run it enough , I've only had it on muff so for. Boat set up for 5 years from the gentleman I got it from, I have changed the oil and replaced water pump 2 months ago but haven't messed with it much except fresh gas and oil mix.
 
oldboat1

oldboat1

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no offense, but easy to over rev on muffs. As you replaced the coils, I would do a compression check. You may need head gaskets, for example, and could check for ring issues with head covers removed.
 
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tom5410

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I will do that in the morning and I read the sticky on carb adjustment, I will try that to. no offense taken. I really appreciate the response, I couldn't think of what else it could be. thanks I'll post readings when I get them.
 
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racerone

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ECHO----The parts books do not show any carburetor mixture adjusting screws for a 76 model 85 hp !
 
Joe Reeves

Joe Reeves

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Puffs of "white" smoke?..... White smoke = water. Do a compression check!

Needles and adjustments were made by another member or you?..... There are no adjustable needle valves on that engine... only fixed jets that must be securely tightened snugly.
 
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tom5410

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Well I checked the compression, not good after letting it warm up I had #1-15 #3-25 #2-25 #4-15 wow what a difference from 2 months ago.
 
ondarvr

ondarvr

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It won't run with numbers like that, check it again, maybe with a different gauge.

What were the prior numbers?
 
Joe Reeves

Joe Reeves

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tom5410 said:
Well I checked the compression, not good after letting it warm up I had #1-15 #3-25 #2-25 #4-15 wow what a difference from 2 months ago.
Click to expand...

Have you, by any chance, loaned out this rig to a trusted friend, relative, anyone who has suddenly kept their distance from you?? Compression readings such as that coupled with puffs of white smoke spells out someone ignoring the overheat horn warning and running the overheated engine until it seized to a smoking screeching halt!

Check the plastic components of the engine to see if they've melted down somewhat. Let us know what you find.
 
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