1990 90hp to a 1993 120hp swap

[pita482]

Hello, first let me say thanks for any response in advance,
So I'm currently running a 1990 bayliner 1800 Capri with a rebuilt 90hp with cdi ignition I rebuilt 5 yrs ago, I just recently rebuilt a 1993 force 120hp with the thunderbolt ignition and getting ready to do a power head swap.
So my question is, is anybody familiar with the #8 wire red/purple coming from the engine harness to the boat?
Not sure if this is a power wire that is supplies power back to the ignition
switch, and if so do I need to use it?

 

[pnwboat]

From the wiring diagram, it looks like the red purple wire is the 12 volt supply from the battery to the ignition switch. It runs through the fuse. You need that wire to supply 12volts to the ignition switch. Without 12volts to the ignition switch, nothing connected to the ignition switch will work.....starter solenoid, accessories, lights etc.

 

[pita482]

I agree but my 1990 90hp doesn't have that wire, so something is already supplying power to the switch,
The only wires I have from my boat harness are the
Start wire
Tach
Temp
Stop
Choke

 

[pnwboat]

I would think that the red wire on your 1990 90HP motor serves the same purpose as the Red/Purple wire on the 1993 120HP. Do you have a red wire on your existing ignition switch?

 

[pita482]

The only power coming from the boat to the 90hp engine is the yellow/black start wire wich goes to the solenoid,
The other wires coming out of the harnes to motor are stop, choke, tach, and temp, my ignition has to be powered from the battery I'm assuming, I haven't looked yet

 

[jerryjerry05]

You HAVE to have a power lead in the harness.
​It might not feed right into the key?? but will get there maybe through a fuse block??

The buss bar on the motor should have the harness hooked to it.

 

[pita482]

Thanks everyone for your response's, ignition is powered from fuse block under dash, my 90 had a red wire going to buss bar on engine but nothing hooked to the other side that leads into boat, the 90 1800 Capri key switch is powered from the boat not from the the motor like 93 and above, thanks again for all the response