1990 125 johnson

cobia205

Cadet
Joined
Jun 3, 2023
Messages
10
I have a 1990 125 Johnson outboard (J125ESXESS) and it had a bearing going out in the lower unit , so I replaced the whole lower unit and the first time I took it out , it will not go past 4200 rpm and will not get up on plane , it was a used lower unit off of a 79-91 Johnson with 25" shaft , the lower unit is the only difference from last season but I don't see how that could be my issue as it spins freely , I put a new water pump in it and the gear oil looked good but I changed it anyways , used my old prop and vro was bypassed a long time ago also.

What is the easiest way to diagnose my problem. I believe it is spark related as pumping the primer makes no difference and pushing the choke in actually makes the motor bogg down. It has a spin on filter and a clear see through filter up by the carbs that only has about 6 hours run time on it and the whole fuel system is less than a year old , the carbs are opening all the way and the timing linkage is moving all the way. Any help is GREATLY appreciated !!!
 
Last edited:

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,451
Check for water in the fuel.----And as always post your compression test actual values.----Then do a spark output test.---Does spark jump a gap of 3/8" on each lead ?-----Might be running on 3 cylinders.
 
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