40hp outboard mercury

[lonestar]

hi everybody, i have a 1976 40hp mercury 2 cyl. outboard and when i am
cruising at 3/4 throttle it runs great but when i go to full throttle it starts
to jugg, stubble, and then die, but it starts rit back up and i can go
but it does the same thing again. any help or suggestion needed.
thanks
lonstar

[marshmat]

I can think of two things that might be involved: fuel, or ignition. It's possible that your carb is getting a bit clogged and can't flow enough fuel at wide-open, causing it to go lean and start sputtering. It could also be a problem in the ignition system- check the spark timing, the plugs, coils, etc.
Anyone have any better ideas?

[SmithCraft64]

Whens the last time you changed or blew out your fuel filter? Check your carb adjustments. It may be starving on the high end. Hope these suggestions help you.

[PeO]

Curious about the results... I think I have the same problems at my Merc 650 -1970....
I have owned it for a mounth and there was no diafragm in the fuel-pump when I bought it..
Now I have put in the parts and tryed agian... It runs smooter but with full throttle it runs up to a minute then it slows down...