msd or carb
 

I am having a hell of a time getting my mag to run perfect......It seems to be electrical.....will a msd make the boat run eratic,almost like you have a severe rich condition in the motor.;....It is between the 3000 and 5000 rpm range, right where i nedd the most power...it will cough, fart and sometimes almost stall before i can get it on plane

sounds like a carb problem. Also check your timing.

Went through all that timing is perfect, no matter what i change jetting or air bleeds the problem stays there........It is real erratic....sometimes it runs graet other times runs like ****

Bad coil acting up when it gets hot maybe.
are you running a 6al or like or ar you running the tbIV

6al and a hvc coil, i am leaning toward the box or coil because it is the only thing i have not broken or changed on the motor in a year and a half....

then thats where i would start.

Good luck

Do you have 'blackening' inside the cap where spark has been arching between contacts ?
I had a pro-billet distributor with excessive corrosion on the trigger rotor and magnetic pick-up that gave same symptoms.
I too chased thoughts of fuel issues, turned out to be ignition breaking down above certain RPM.

Nosmokes, I am chasing a similar problem with a Crane box. Spoke with a person who suggested and has seen electric fuel pumps kick out an RF signal the pizzes off the igntion system. Might try running 12v straight from the battery to the coil. Just be aware turning off the key will not stop engine, got to hit the batt. switch to off or switch from 1 to 2 etc.

Never switch your batts to off while the engine is running unless you want to buy a new alternator.

have small amounts of carbon traking but nothing out of the ordinary.....going to try a new box this weekend

I Hads A Similar Prob Ended Up Being A Cracked Spark Plug Chased It For Two Weekends I Feel Youre Pain

ran through the plugs twice ...........I thought that also going to try it with new box and coil tommorrow

going to try it tonight....New box and coil see if that was it..........Man this magnum has been exspensive.....