1988 Mercruiser 3.0 sterndrive stalls when returning to idle

rehgarde

Cadet
Joined
Jul 14, 2016
Messages
8
I have a 1988 Mercruiser 3.0L 181 CID 130hp sterndrive engine that is having the following issue.

Starts fine, holds a low idle at 600-650.
Shifts into forward/reverse and cruises along slowly no issues. Can leave the dock at slow speed in reverse, stop then move into forward and cruise along fine.

***When trying to throttle up, sputters and almost dies, hesitates when trying to push to full throttle, but then catches and goes along fine, up to 32-35mph. This happens if I am easing into it, or pushing forward faster to simulate pulling up a waterskier.

***AND, more troubling,, when returning back down to idle slowly, or to go into neutral, it always sputters out and stalls. The engine will start back up without an issue.
I have tried slowing down in increments, or very quickly, with the same result each time. Little problematic when I think it is OK, then it stalls as I am reaching the dock!

Last year we had the shift controller replaced, the accelerator pump replaced. This year it has all new plugs, new cap, points, condenser, and new ignition coil. Gas is end of last season but had stabilizer in it. Also timed the engine to 8, but see now it should have been 6, so I will adjust that tomorrow.

What is my next step in diagnosis/repair of this issue?
Thinking either carb needs a good rebuild/cleaning, or a problem with the shifter adjustment?

Thanks for whatever help you all can give!
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,542
You should repost this in the I/O section.

A lot of those Mercruiser sterndrive motors have a shift interrupter which kills spark to the motor, for an instant, when shifting is hard. If your lower shift cable is binding or the motor speed is high, the ign will be killed for a longer time, possibly stalling the motor.

Look for a roughly triangular fitting on the shift cable on top of the motor and you should see a micro switch and two spring levers. That fitting must spring back to it's center to restore spark. If it hangs up the motor will stall.
 
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