90 hp motor stalls when I accelerate boat

[berndie61]

Hello,

if I accelerate the boat, motor will often stalls. With motor in water, no gear I can always give throttle and motor will not stall. In gear when I will accelerate the boat motor often stalls. After that it's hard to start again. I checked compression -> ok. I checked timing TDC = 1, BTDC = 30. New spark plugs. I'm a bit desperate - motor sometimes run and sometimes stall. I can't see any relation between behavior of the motor and a possible fault.

Questions:
has this phenomena something to do with the ignition, CDI or with the carbs or fuel?


berndie

 

[roscoe]

Re: 90 hp motor stalls when I accelerate boat

Most likely carbs.
Is a symptom of running lean, which will burn up your 2 cycle motor.

Carbs need to be torn down and cleaned.

As a possible TEMPORARY fix, you could open the idle mixture screws by 1/8 turn.

 

[berndie61]

Re: 90 hp motor stalls when I accelerate boat

I checked the carbs. The nozzle in the middle carb was a bit clugged -> I cleaned it.
In the upper and middle carb the inlet needle sometimes stuck. I replaced all three inlet needle. Now it's much better but not perfect. If the boat is running with 25% throttle for a few seconds and afterwards I acclerate the boat the motor sometimes die. Motor will not accept more throttle. I assume this has something to do with a lean run. It tried the idle mixture screw at 7/8 and 1/1
turn out from slightly seated, but I can't see any change or improvement. Timing is ok. I have another problem : motor is not running with constant rpm Motor is running between 1000 - 1200 rpm in water in idle mode with no gear.
Please advise.

Berndie

 

[foodfisher]

Re: 90 hp motor stalls when I accelerate boat

Cleaning the recirc. (fuel) system, I went from hard start to instant start and minimal smoke. 1 to 11/4 turn out on carb adjust. May clear up some of the probs.