Totally stumped.. 1990 150hp Yamaha missing

[Whaler1777]

Hello everyone, I am hitting a wall here... I have a 1990 v-6 150hp Yamaha outboard on a 19' Grady White, running on 4 cylinders..(port 2 lower cyl's are not firing) This motor has 214 original babied freshwater hours. Boat sat unused for a while indoors in a nevada garage. Prev owner stated he felt some hesitation (missing) last time he used the boat... The compression in all cylinders is right on the money 123-125 each cyl, all of the ignition coils are showing spark(I even tried switching them around got nothing on the 2 cyl), carburetors were rebuilt a week ago by my mechanic (fact. trained) NGK Spark plugs are 1 day old and gapped perfectly, oem yamaha fuel pumps are both 1 day old... I really feel that there should be nothing stopping these cyls from firing.. Any suggestions as to what else I should look or what you think it could be would be GREATLY appreciated... Thanks again, John

 

[DadTo2Marines]

Re: Totally stumped.. 1990 150hp Yamaha missing

Your CDI unit, pulser or charge coil is out. More then likely its the pulser coils as 1 each is used to power two cylinders.

 

[Whaler1777]

Re: Totally stumped.. 1990 150hp Yamaha missing

is that pulser unit located below the flywheel? and off hand is there any way to test its functionalty before pulling the flywheel? Thanks, John

 

[rodbolt]

Re: Totally stumped.. 1990 150hp Yamaha missing

like I keep hammering, test compression, test spark then go fix the fuel system.
a 1990 V6 150 is about one of the easiest CDI ign systems to test.
use of a peak reading multimeter is mandatory.
buy the meter, test the pulser coil output,the charge coil output and the CDI output and its done.
seirra sells a decent analog meter for about 116 dollars or most modern digital meters will accept a DVA adapter.
but with two on the same bank dead your not describing a pulser coil issue.
this so called factory trained tech should have tested it when the carbs were done.
so much for training.
I can train a monkey but that doesnt mean he wont leave banana peels everywhere.
pulser coils on this engine fire 1-4,,2-5 and 3-6, see why I say its not a pulser and not a stator and most likly not a CDI. testing is always a good thing as none of the parts are cheap.
and once you buy them you own them.
so buy a meter, the seirra eqivalent of the mercury marine meter with a builtin peak reading function works well for the money, buy a copy of LIT-18559-84-05 from your local dealer and go fix this beast.