1985 75hp mercury no spark on cylinder 4

Beckerd07

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Joined
Aug 19, 2018
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2
Ok so I’m trying to figure out why I’m not getting spark on cylinder 4 (verified using a timing light). I was having a problem with the boat not wanting to run over 4000 rpms, previous owner had installed an electric fuel pump because they didn’t want to rebuild the mechanical fuel pump. So I rebuilt the mechanical fuel pump bypassed the in line electric fuel pump and now the motor will start and idle for a short period of time then die off almost like its losing fuel. Cleaned and rebuilt the carbs still same problem. Pulled spark plugs to see if any were getting wet and saw the number 4 plug looked brand new like it hadn’t been firing. Put a timing light on and I’m not getting any spark. Spoke with the shop by my house and they’re saying it’s either going to be the coil (least likely in his opinion) switchbox (the most likely) or the reed on the crank. Is there any way to test the switch box to figure out if that is in fact the issue? From my understanding of I’m not getting voltage at the coil that still could possibly not be the problem and the problem could be at the switchbox. Thanks for any help anyone can give me, I’m pretty new to troubleshooting and working on outboards so any help is appreciated!
 

Beckerd07

Recruit
Joined
Aug 19, 2018
Messages
2
Switchbox......

Are you saying the switchbox is likely the culprit? I don’t like just throwing money at a problem. To me it sounds like that would be the most likely issue. From what I’m getting reading other forums if the stator or flywheel were the issue I would have no spark on at least 2 cylinders which is not the case and the coils on these things aren’t real bad about not working. Not saying they can’t go bad but they’re least likely to be suspect, more so the powerpack seems to be the weak link or so I’m hearing. Is this right?
 
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