Motor swap. Merc 140 now tach not working

[m*a*baity]

I have an 81 Caravelle. Blew a head gasket so I got another motor from an 86 Starcraft. Both are Merc 140's. Got them swapped out and all is well minus some fine tuning. My tach isn't working now. I have 2 wires I haven't hooked up yet. I think those are my trim gauge wires they are black and orange/white. Am I wrong or right? Where are some good places to start checking? The tach worked before. Any suggestions? Thanks fellas.

 

[Bt Doctur]

Re: Motor swap. Merc 140 now tach not working

The tach feed is usually a grey wire connected to the neg. side of the coil

 

[m*a*baity]

Re: Motor swap. Merc 140 now tach not working

What about the Orange/white. Is that the trim gauge wire?