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intermitted spark runs great and then like poop.

mike70hp

New member
Hello,, looking for some help I have a outboard 70 hp johnson that fires on all three cylinders when cold, Once it warms up,, i loose spark on cyl 1 and 3. I replaced the power pack and it made no change, I tried testing it per the manual but seems a bit confusing, I tested the stator and it failed, and then passed once cooled off, Has anyone ran into this before or can offer some advice, The only other part was the timming base.but since it fires when cold, i dont think that would be the issue, any help ??
 
Model number please?

J70VLSIS I believe it when it gets to the point that the power pack kicks off the quick start that it starts to run poorly. Start right up and runs great cold, once its warmed up and drops cylinders, it stays that way until the engine has cooled and then the process repeats itself.
 
Perhaps the S.L.O.W.----system kicks in.-----Bad sending unit.------Worked on a 1998 model 70 HP last week where somebody had run the motor with no cooling water to the impeller.----So also check your water pump !
 
I've owned the boat for years, never ran it without water pumping thru it. going to do some more testing today, Thx for the reply
 
Sorry----I can not stand beside your motor to diagnose it.-----I just toss out wild / no money spent ideas for folks to check out.----Good luck with your motor.
 
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