motor has a miss, has for a while..

ok, been posting the last couple months about my boat i got this summer, and its 82 50hp mercury..

it never wound up like i thought it should, so i thought it needed a prop.. well have determined it did indeed, and it runs better.. but now that it isnt lugging so much, i can detect at higher rpms, it has a miss.. now i dont know if it is a all out miss or spiratic, but it is more evident at higher rpm.

so i changed the plugs today.. the top two had some carbon buildup, but nothing bad, the third had less carbon but some, and the 4th - the one on the bottom looked like a brand new plug?!

so i replaced them all with new NGK BUHW-2 plugs, but i pulled the plug wire on that fourth cylinder, and the contact on the coil side is all black and cruddy.. i am gonna get new plug wires, but if the wire is in such bad shape, what are the odds that that the coil side isnt corroded and ruined too? anyone got a part # for the coil? do you replace one, or all 4?

i suspect it hasnt been firing since i got it.. has this caused damage by running fuel mix through without combustion? or with spiratic or weak combustion??

i havnt done a compression test on this cylinder, but that is next i think..

opinions?

Re: motor has a miss, has for a while..

got a cheap plug wire at o'reillys today, and took it to a lake nearby.. no change.. i looked up the coil here on iboats, and went ahead and ordered one, and 4 new plug wires while i was at it.. we'll see how that works out..

ok - the plug was like new, the other 3 were carboned up and obviously different.. i jump to no spark? but what if the plug is sparking and there just isnt fuel flow? or no compression? what would the plug look like? am i looking the right direction?

i suppose i could just disconnect the suspect cylinder plug wire altogether and see if it runs any different? would this be a bad idea?

thanks for readin