I'm not a motor-head, so please excuse the relative noob-ness of this question, but here goes...

We have a 4 cylinder Mercruiser motor in a semi-beater family boat. If I had to guess, I'd say it is a mid-90's vintage motor. The problem is the motor falters and can stall when you try to accellerate the motor past about 1800 RPMs... This behavior disappears when the motor is REALLY warm, but in general happens for the first 15 minutes of operation each time we get the boat wet. If I'm very careful I can get the motor to come up to speed, it's just delicate... Almost sounds like the motor is flooding, but remember my assessments should be treated skeptically because I'm not a mechanic.

My question -- what an *I* try before taking to a mechanic? Will carb cleaner and/or a product like seafoam be worth trying?

Thanks to any and all suggestions!

sounds like the choke is out of adjustment or not working at all.

Sounds like the choke plate isn't getting to the full-open position on time. I would say that within no more than 5 minutes, the choke plate should be full open if it is an automatic choke.

It may use a bi-metal spring to operate and it should be adjustable....observe the operation of the plate during warmup.
Don't burn your whiskers off

If it turns out to be a choke problem and the automatic function can't be made reliable, you can install a universal, manual choke control.

I'm no mechanic either but I would try the Seafoam... If it doesn't fix it all you are out is $10.

For what it is worth, my old Harley was running rough after sitting all winter so I ran a little seafoam thru it and It started running good again...

The choke ideas are interesting -- I'll dig in there a bit... I've operated motors with manual chokes plenty of times, I'd have presumed they would be hard to START -- or is it stuck OPEN? (and hence flooding when I throttle up?)

Is the idea that the automated choke goes open/rich, then when you throttle up it closes up for a leaner mixture? In other words it only is running rich when you idle/cold?

No, closed is richer....it goes to full open when engine reaches operating temp.
Bear in mind that "closed" isn't fully closed.....maybe 3/16" open.
Each carb has its own specification for this "cold position".

Thx all ... ordered a shop manual too -- it's high time I learn a few things about motors. Since car motors are so complex these days, methinks this mercruiser will offer some good lessons.

run some carburetor/fuel injector cleaner thru your tank too. Its highly likely your problem was cause by gas that set in your tank too long and
it turned into varnish in your tank and gummed up your carbs.

I agree with chuck had same problem on a Volvo it was the excelerator pump. cheap easy fix.

Since it starts and runs, but bogs down or dies upon acceleration, I'd put my nickel on the accelerator pump as the problem. You can have someone else open the throttle, or disconnect the control cable at the carb so you can open the throttle by yourself. Now with the engine off, air filter off, key off, and choke plate held open, you should be able to see down the throat of the carb. Each time the throttle is opened there should be a squirt of gas (visible with a flash light) injected down the throat of the carb. Without that squirt of fuel, the engine will hesitate, balk, or stall when accelerating, especially true when engine is half warm as the choke has opened, but the intake manifold is not yet warm enough to vaporize the gas effectively.
If this confuses you....don't do it yourself. Have someone go through the carb for you.
This advise is worth exactly what you paid for it.

"This behavior disappears when the motor is REALLY warm, but in general happens for the first 15 minutes of operation each time we get the boat wet."

Choke issue because symptoms fade as motor warms up. Accelerator pump would be a constant issue, not affected by engine temp.

Yep, I threw down on choke because of that report.

Wrong.....it's not a car with immediate acceleration. Boats wind up slowly, so the accerator pump has minimal effect when warm. My 2

Let's put it this way.....looking down the throat of the carb to see if the pump is working is a dead give away....It's the first thing I would check, rather than screwing around with the choke before verifying that the pump is functional. Good Enuf?

No.
How much ya throwin' down ?

I believe I have the same problem on my 1989 Maxum ski boat. From what I've been able to read online, it looks like it's the accelerator pump. I bought a complete carb rebuild kit, but would like to replace just the accelerator pump and test to see if that's the issue.

Can you guys tell me if the accelerator pump can be replaced without removing the carb?

The real issue here is:

Yet another post involving "Mercury + Problem"

An expensive lesson I'm still dealing with.

I very much appreciate all the thoughts, I've gotten her open and with shop manual in hand did take a good look at the choke -- It *did* seem stuck, and a little gumout and clean towels later she's not stickin'. Still may have other problems but weather and family life will clear this weekend and I'll give a more detailed report..