Merc Outboard stalling under load

I've got a 2005 30HP 4St Mercury outboard motor that's intermittently
stalling/losing power under load. It'll run fine boating around or at
idle, but wide open say pulling a tube the motor bogs off and on
(off/on, off/on, about a second or two apart).

Had the problem last year, the marina replaced both fuel pumps - which
made sense to me the way the motor is acting. Unfortunately it's doing
it again this year.

Any ideas on what could cause this?

gcook wrote:
> I've got a 2005 30HP 4St Mercury outboard motor that's intermittently
> stalling/losing power under load. It'll run fine boating around or at
> idle, but wide open say pulling a tube the motor bogs off and on
> (off/on, off/on, about a second or two apart).
>
> Had the problem last year, the marina replaced both fuel pumps - which
> made sense to me the way the motor is acting. Unfortunately it's doing
> it again this year.
>
> Any ideas on what could cause this?

I've done a bit more investigation on this and may have something
different. The marina suggested that it may be cavitating. Now that
sounds fine to me - but if it is cavitating:
1) should it be cavitating all the time? i.e. every time we're going
down the lake and I tilt the motor up to put it on plane it starts this;
it basically won't go up on plane.
2) if it is cavitating, is there a fix?

The marina kind of shrugged as if there's no solution if it's
cavitating. I don't want to accept that this is normal behavior
however, since it does it on an ongoing and sustained basis.

(I'm still not 100% sure that it's cavitating or that it's a motor
problem as I haven't had the opportunity to be in the boat with another
adult since my last conversation with the marina).