Morning folks- I have a 2003 Bayliner with a Mercruiser 3.0 engine. Current issue is I have no spark from ignition coil. Used spark tester and inductive timing light and the coil is not generating a spark. I've tried three ignition coils to date. Currently isolating the ignition coil to troubleshoot. What should the voltage be going into the coil when cranking? I'm currently at 1.1VDC into the coil via a purple wire when cranking. If I understand the drawing correctly the purple wire appears to be powered from the alternator. What should the volts be on the purple wire from the alternator also reading? I'm currently at about 1-2 VDC directly out of the alternator. I'm using an ACDelco D503A Ignition Coil.
Is my alternator wired incorrectly?
Are enough volts making it to the ignition coil to generate a spark?

How can I best troubleshoot this? I've thrown too many parts at this at this point.

Thanks for any feedback.

Purple should be your 12v ignition circuit and have 12 volts on it with the key on or ignition switch on.

Thank you. Any reason it would be reading so low from the source (the alternator)?

Okay, purple wire is at 12v with key on and/or ignition switch on from the alternator and going into the ignition coil. Purple wire going into coil is also at 12VDC when cranking. I'm still not seeing a spark from the coil wire. Any advice?

check voltage in and out of item #3 in your pic

Yeah, it won't start with that low a voltage. get the battery up to full before proceeding.

From that diagram it looks like your distributor is what times/triggers the spark. You could pull the coil and bench test it with a battery and spark plug, but my guess is the distributor is not working correctly.

Do you have about 12v at the 10pin plug on pin 5(purple) in and out of plug with key on?

Purple wire should always have 12-14 volts with key in on position.
Check your voltage at the ignition switch.

He has 12v with the key on on purple. Need to look at the distributor next. It provides the ground for your coil. You could pull the coil and bench test it.