Ok I replaced the plug wires, the , the starter, the ignition switch, the distributer cap, the rotor and sensor and the dam thing will not start, The battery was replaced as well, what could it be? The engine is a 454 420 merc. do not know what to do. Any thoughts?

Kill switch? Shifters in netrual?

Do you have fuel squirting from the squirters when you push down on the accelerator pumps? Do you have any spark at the wires? 12 volts at the purple wires on the coil with the key on?

Let us know.

John

yep . . . did it once myself . . . spent every bit of an entire day replacing stuff only to see a life vest laying on the deck with a lanyard dangling from it . . . we had just thrown in the towel and started drinking when we saw it . several hundred dollars were spent along with several trips to BoatUS

Neutral safety switch???

neutral safety switch will disable the starter so it will not crank over at all. kill switch disables the ignition. if its a fuel delivery problem it may still "try" and start. might act like it wants to catch but will sputter and quit. if its an ignition or kill switch it will crank without change.

It acts like it wants to start but dose not.
What is the problem with fuel delivery?

fuel pump or plugged filter or line. check the filter/water seperator. make sure all lines are un obstructed. should be able to blow through back into the tank.

Assuming you've already made sure you have spark.
If it's carburated prime it with a splash of gas down the carb. If it starts and dies you know it's a fuel delivery problem. If it's injected you need a pressure gage.

not an alpha, is it? if so, there's a stupid little ignition interrupt switch for when you shift that can go bad and screw you. if it's acting like it wants to start, ie firing a few times and dying, that's probably not it.