Gentlemen, Gentlemen,
After being a Service and Parts Manager for 25 years. This is your laugh for a few days, maybe a month

Michael gets the dumbest award for December.
First thing I always preached to my mechanics, follow the trouble tree. I don't care if you replaced part #1 last week, follow the trouble tree and start from the beginning. Look at the schematics and what do they say to you?
So Michael, took for granted I had a fuel issue, which was my first mistake. Having just filled up with fuel I took for granted it was somehow fuel related. I was convinced of it, so I replaced the fuel strainers on this 7.4 MPI Fuel Injection 454 engine. Still would spin over, so I swapped sensors from each engine, nothing. Disconnected the batteries and swapped ecm's, nothing. Went out an purchased a $100 really nice fuel injection kit. Got pressure specs from your fine gentlemen and they were 42-44 and right on the money. I replaced the ignition switch..
Then summer hit and my
3 businesses consumed my time. I have tried everything except checking the spark, which should have been where I started.
We slow down a little bit in November and December, so I was determined to get this port engine started.
There is no way it could be spark? New wires, New plugs 100 hours ago and no way in hell it could be a distributor cap or rotor button. Right!
Wrong, I took the button up and it had a little corrosion on the shaft, button looked fine at first glance and would this really cause the engine to die? Yes indeed
So the button had a hairline crack on it as shown. So I drove to an auto parts store, one that seemed to have more GM parts when I searched online.
So I walked in a gave them the button. Make and model of your car sir, 1998 Carver 405. Say what
Yes I will be ordering 2 new Mercruiser caps and rotor buttons, I just wanted to know if the damn thing was bad with a hairline crack. Guys were really helpful and had just buttons in stock. Sir, would you like the aftermarket or the GM version, it is a $6 difference. $3 compared to $9 and I took the GM version naturally.
Getting back to the boat, I cleaned the distributor shaft and installed the new button.
Put the cap back on and convinced myself it could not be this simple.
Turn the ignition and the port engine started purring like a kitten immediately. I mean started immediately as soon as I hit the key.
So guys, I am here with egg all over my face, in the hope this helps someone down the road. Ya were the bomb with everything you offered or suggested I do. Why do men have to be so damn hard headed and stubborn?
Thank you for your knowledge.
Michael