No spark on 99 90horse

M

mmarzella

Cadet
Joined
Dec 10, 2011
Messages
8
Just bought this boat Motor starts easy at ramp. After 15 minutes of idle try to jump up to plane and motor is very hesitant and feels like its shutting off and on quickly almost like I'm running aground intermittently but I'm not. After shutting of engine, it wont start. I pulled the plugs, no spark. Get a tow home. On the hose in the yard 2 hours later., fires right over. Some have suggested powerpack, about $225, some suggest optical sensor about $70. I have read that you cant test a powerpack. Im about ready to pay the $95 per hour mechanic to check it out. I believe my fuel system is 100%. This is a 1999 Johnson 90 J90PLEEB. Thanks for any help.
 
B

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: No spark on 99 90horse

First off disconnect the black/yellow wire from the pack. This eliminates the boat wiring harness. If still no spark it's either the pack or the sensor but you need the equipment and manuals to check it out. It's a 50-50 chance on which one it is.
 
M

mmarzella

Cadet
Joined
Dec 10, 2011
Messages
8
Re: No spark on 99 90horse

Dont have the manual or other equipment. I will try and get the manual. So just for clarity. I should unplug the wiring harness, then try starting. Will I have to jump the starter since the wiring harness has been disconected? I actually have borrowed a spark checking tool. I assume that if I get spark then that the problem is forward of the wiring harness? Is there away to check the optical sensor, or the coil packs? Its confusing that I have spark intermitiently. Thanks
 
B

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: No spark on 99 90horse

All you have to do is get the black/yellow wire out of the system. Look closely at the pack. OMC built a tester for the sensor but it wasn't very accurate. What I usually do when I run into this prob is replace the sensor first (easyest to do) and then try it. Still no spark, then the pack. This of course is after disconnecting the bl/y wire and checking stator and power coil output with a peak reading or dva meter.
 
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