1990 Mercruiser 4.3 help!

I've got one that's stumping the hell out of me.....
Its in a Rinker 206 Captiva, MerCruiser 4.3, serial number OC767123.

The complaint was that the engine was running fine, then just died. Like someone turned the ignition off.
Its got the Thunderbolt 4 ignition, and I went through those steps, which are as follows:
1)Connect voltmeter ground to good ground, and positive lead to white/red terminal at the distributor.
2)if you read 12 volts, remove spark wire from coil, and hook up a spark tester. Take white/green lead from the distributor, turn the ignition on, and strike the white/green to ground. If you have spark, replace hall effect sensor in the distributor
3)no spark in step two, install new coil.
4)no spark from step three, install new ignition amplifier.....

Is there something I'm missing/ Because at this point, I've replaced the hall effect sensor, coil, and amplifier, and still have nothing.

Next steps;
1) disconnected the grey wire from the coil, thinking bad tach. Nothing.
2) disconnected shift interrupter switch. Nothing.
3) one thing I did notice, when cranking this engine after each try, the oil pressure isn't reading squat, the tach never did.

Is there something I'm missing? It cranks like hell, but acts like theres a blown fuse or something.

Any help that anyone who works on these more than I do can give me would be invaluable.

Thanks, good people!

You have 12v on + side of coil when this is happening ? and under load - so if you hook a voltmeter to + coil and trigger the ignition like above by stiking the white grren wire to generate a spark it doesnt drop ? Only thought is if you are loosing voltage when the coil is building energy? ??

Hopefully Chris @Dockside Marine will troll through here he should have some ideas for you

Dieter said:

You have 12v on + side of coil when this is happening ? and under load - so if you hook a voltmeter to + coil and trigger the ignition like above by stiking the white grren wire to generate a spark it doesnt drop ? Only thought is if you are loosing voltage when the coil is building energy? ??

Hopefully Chris @Dockside Marine will troll through here he should have some ideas for you

Click to expand...

No, its not losing voltage at all. Maybe .5-1 volt when striking the white/green wire. But still no ignition being produced from the system at all. It's almost like there is a fuse blown, and if there is, I'm not seeing it.