Old 70’s Johnson engine swap

[mtlunder]

So I have a 17.5 foot lund with a 1976 135 hp outboard on it. The motor starts fine and runs fine not under any load, but when I’m on the water it dies out at about 3/4 throttle, I swapped the spark plugs hoping for a simple fix, but still have had the same issue. Does anybody have any experience with these older motors and maybe know what could be happening? I also have a 1972 65hp johnson that runs perfectly, I’m wondering if I can swap the motors by simply disconnecting them at the large fuse holder just inside the motor, just hard to find any good info on these older Johnson’s now days. Thank you in advance for any help you might be able to give.

 

[racerone]

The 72 model 65 hp is electric shift.----Big yellow plug on the motor.------Not a direct hook up.

 

[mtlunder]

The 72 model 65 hp is electric shift.----Big yellow plug on the motor.------Not a direct hook up.

Is the 76 not? It’s got a red one of the exact same size

 

[racerone]

Electric shift was last used on 1972 models.