Project boat, no spark bad to worse

I just bought a Sea Sprite with a Mercruiser 120. The boat is a winter project that has potential with a great trailer, hull, solid floor, no seats but he gauges all seem to work and light up so far, trim works, and the motor appears clean on the outside for what it's worth. So it was said to run great a couple years ago. It's been turning over good and seems to get fuel but no spark. I was in the process of checking the coil and read here somewhere that the Tach could be bad and causing a ground and in turn causing no spark. So while I was checking things out I removed the grey wire from the coil as I thought thats what I read how to check on the bad Tach. Tried to start it and nothing, I mean absolutely nothing, no cranking....dead. So I re-attached the grey wire, tried starting and heard a small bump or tick almost like the motor bumped over ever so slightly then stopped. Then dead again. Wont crank. Battery is great. So now I'm worse off than no spark. Anyone have an idea what I may have done or is this just a freak problem that would have happened in any case. Very strange. Maybe a shift cable problem? Like it thinks it's in gear? Hard to believe the grey wire had anything to do with this?

The grey wire is just a tach signal from the coil. It won't stop the engine from cranking. What year and SN of the engine? Points ignition? The key switch turns on the slave solenoid and that sends battery voltage/current to the starter solenoid. Try jumping the slave solenoid to see if the starter cranks. If it does crank it then check the yellow/black striped wire at the base of the solenoid for 12 volts when the key is turned to start...shifter in neutral. If there is 12 volts there then the solenoid is worn out or the ground is not making contact to the solenoid.

If there is not any voltage there then check the yellow black wire at the keyswitch for 12 volts when the key is turned to start. Still no voltage then the keyswitch is bad. If it is there then jumper the neutral safety (NS) switch...look under the dash in the wire harness near the shifter...you should see 2 yellow w/black stripe wires...jump them w/a blue quick clip connector. If the solenoid now gets 12 vdc then the NS switch is bad.

If jumping the slave does not crank the starter then check the battery side of it for 12 volts. If it is there then go to the starter and remove and sand clean both ends of all of the battery cables. Start w/the battery ground and leave it disconnected until you complete them all. Reconnect all cables...the ground is always first off and last on. If it won't crank then the starter and/or its solenoid are worn out.

If you have to pull the starter don't force/break the mounting bolts. Use PB Blaster or other penetrating oil to soak the bolts. If one going into the engine block still won't budge let us know. A small hole can be drilled on the top of the area where the bolt screws into the block to allow lubricant to reach the bolt threads. Good luck...keep all informed.