merc 120 engine swap, electric problems now

[stillstrokin10$$]

I swapped out a bad mecruiser 120 for a good one. I had it running well while it was hanging from the cherry picker, but now it will only fire up while i hold the ignition down and as soon as i let go of the ignition the motor cuts out.
When i had the motor running good it also had its original wire harness.
I installed my old wire harness on it from the bad motor and may have put a wire in the wrong spot because the wires were not the same colors as the other harness. I am not sure how to trouble shoot this problem and any replies would be greatfully apreciated thanks

 

[fat fanny]

Re: merc 120 engine swap, electric problems now

go up to the adults only section of this forum and download the correct service manual for your engine and it should have the scematic for your harness as well as the one from your old engine pretty straight forward w/ the scematic. Good luck

 

[Don S]

Re: merc 120 engine swap, electric problems now

Head up to the adults only or DIY sticky at the top of this forum. (second and third posts) download the OEM manual for whatever year engine you have and you will find wiring diagrams in the manual.
You seem to have the wire from the ign switch to the coil missing. It's a resistor wire.