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please help with a weird problem

J

jhalleqdt

New member
Hi all and thanks for letting me join! I need some help with a seriously weird problem. Ok....1984 mercury 150 blackmax. Rough idle, sometimes wont start, miss fire at higher rpm. Here is why this is a weird problem. At first we thought a powerpack because #3 wasnt firing. Changed it out with a dif one and still didnt fire. Changed trigger 3 times, still no fire on #3. Checked coil, its fine. Here is where it gets weird. Put org trigger back on, but, switched power packs around. Now #3 fires great, but, #2 is not firing. Anyone know what could be going on?
 
J, Could you be trying untested used parts? Or perhaps parts from a motor that ran well, but you didn't switch over the stator, or do a spark test that ensured 7/16" strong spark on all six?
 
timguy said:
J, Could you be trying untested used parts? Or perhaps parts from a motor that ran well, but you didn't switch over the stator, or do a spark test that ensured 7/16" strong spark on all six?
Click to expand...


We replaced the stator with new, replaced the power packs with new, replaced the trigger with new, replaved rectifier with new. Still no fire on number 2. Coil tests good. We also replaced the plugs and wires, cleaned all connections, and checked all grounds. This motor is driving us nuts!
 
WOW! Need a better tech here than me. Internal short in coil? Occasionally they will short only with voltage applied. Trigger new?
 
So, we finally figured it out after damn near going insane. Apparently the flywheel got eaten up by the old stator which ruined the old stator which ruined the rectifier. It makes no sense, but, after getting another flywheel and stator and rectifier and power pack....we still didnt have fire on #2. Hunny got pissed and switched the power packs and it fired on all 6 finally! Found out if a power pack isnt firing on a cylinder, it could be because the other one is bad. Totally makes no sense, but, had it explained by a guy that was an engineer for mercury that that is what happened. So weird. Thanks everyone for all your help!!
 
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