3.0 Mercruiser seems to hang or seize when starting

[nola mike]

if dwell is not properly set, timing cant properly be set with points.

no money is even spent on setting points. just 5 minutes of time to get the beer, dwell meter, screw drive and remote start button

And your wife's nail file, right?
I guess I still would call that the "timing" part of the puzzle. If he's getting a spark though it should be close enough to start. When I think bad points I'm thinking either coated or gap far enough off to not spark.

 

[Scott06]

Ok. I'm finally back. Here is the situation. I have changed all of the following:

1. New battery
2. New Starter Solenoid
3. New Starter
4. New Spark plugs
5. New carburetor
6. New Distributor Cap
7. New Rotor
8. New coil pack

I did all of this primarily because it is a 20 year old boat and it sat for over three years.
Additionally, I flushed the fuel tank and refilled with non-ethanol gas, changed the engine oil, and lower unit fluid (Understanding this should have no effect on engine start). The only thing I haven't done is check/change the distributor itself and have not checked resistance on the on/off safety switch but the engine turns freely and at times seems to want to fire. Also tested for fire with a spark tester and it was positive. Any thoughts?

Start with some basics -
compression test- make sure a valve is not hanging up
dump a little gas down the carb see if it coughs or runs a bit
try rotating the distributor while cranking it to see if timing is off.

Would agree with Scott - if its points ignition and has sat for 3 years, even though you see spark on tester it might be weak and file and set the points is a good thing to rule out.

If you dump gas down the carb and it doesn't cough willing to bet you have a weak spark. Turning the dizzy while cranking would rule out of timing is off

 

[Scott Danforth]

And your wife's nail file, right?
I guess I still would call that the "timing" part of the puzzle. If he's getting a spark though it should be close enough to start. When I think bad points I'm thinking either coated or gap far enough off to not spark.

unless he is using a gap-style spark tester that shows a spark jumping a 3/8" spark, he is most likely using the cheap little one that simply has a light that lights up. the OP may not be getting a good spark.

the little light-up spark testers will fire at as little as 5000 volts.

dwell time is directly related to coil saturation and spark energy. too little gap means too little dwell. too little dwell means not enough electrons made it to the primary coil windings and the coil magnetic field may not have built up enough magnetic field power to generate a decent spark when the points open and the magnetic field collapses driving the spark on the secondary coil windings.

spark plugs need about 15000 volts to fire under the cranking pressure

a coil spark of 40,000 volts is needed for a spark to jump a 3/8" gap. (the ratio is something like 1000 volts per .001)

and yes, I use the wifes nail files as I can not always find my points files. They also come in handy when sanding the arc traces out of the 240 volt contacts on the air compressor

 

[nola mike]

unless he is using a gap-style spark tester that shows a spark jumping a 3/8" spark, he is most likely using the cheap little one that simply has a light that lights up. the OP may not be getting a good spark.

Fair enough