Hello all, I wonder if anyone has had this issue with a 350 merc.
The story is last week I was out running hard then boat dies under hard load, find out the rotor in the distributor has a snapped keyway so I replace and if flashes right up, head out on the water for ten minutes run it hard and it dies again in the same way as the first time but this time the rotor is still intact, now it wont start at all. When it did die both times it lost all rpm and was chugging as it wanted to idle real rough for a couple seconds then quite.
I notice there was water on and around the distributor from wet people on the back sun deck, maybe a short? Also when I tried to throttle down out of the hole it would bog a bit and needs to be eased up to speed.
It is in a 91 mirage, carb, thunderbolt IV ignition.
Thanks so much for any help.

Did you change the dist cap too??? I would for sure.

#1 Get a spark plug tester and make sure it has spark. All auto parts stores should have one in stock that looks like pic below

#2 If it does, make sure fuel pump is pumping fuel

#3 If it does, maybe time to rebuild carb and make sure to pull out fuel filter in carb inlet and see if plugged.
#3A Check water separator/filter for concomitants and water.

BTW: How he heck does a rotor keyway break while running ? Likely during installation or removal

Yes distributor cap was changed as well. I will buy a spark plug tester and see it that narrows the search. The old cap and rotor was very old and corroded on the contacts, it may have jammed and sheared the plastic key way. I do have fuel delivery as I here it squirt while I pump it a couple times. I should get the carb rebuilt tho that is so true, but I would think it would start a little with it. The spark plug tester is a great start, I will let u know what I see. Thanks a ton all

I had similar issues with my 350 and it was a coil issue.

Yes yes I think it might be the coil. Bought a spark plug tester and tried from coil to cap and no spark, I clean all the connections and still no spark. Coil looks original and in rusty bad shape, have to price a coil out

Does the rotor turn when cranking engine?

+1 on the coil. Had a 305 that would start and run fine when cold but when it got hot it sputtered then died and wouldn't restart until it cooled off.

http://bpi.ebasicpower.com/mm5/graph...2-11-illus.jpg