Runs rough at the start (carb sync)

[st3ph3n]

I have a 1985 115hp Mariner that starts right up and idles good but when i put the throttle to it it spits and sputters and runs rough. After a few minutes of working the throttle back and forth it comes to life and takes off and runs like a champ. It does this everytime whether the motor is cold, warm or hot. Whether I've been running it all day or when i first start it up. It does it after I start it up or after I've been running and back all the way out of the throttle (but not shut the motor off) and try to get back on it.<br /><br />A buddy at work said the carbs were out of sync. I know the motor has 3 carbs but that's all I know. Can someone enlighten me about carb sync and what needs to be done?

 

[Conn]

Re: Runs rough at the start (carb sync)

kinda sounds like it's starving for fuel to me but i'm no expert. pretty new to the boating thing myself. might be the floats sticking shut? fuel filter possibly?

 

[roger3645]

Re: Runs rough at the start (carb sync)

try these two things: At idle spray a mixture of fuel into each carb (one at a time) this should bog down the motor. If rpms increase that carb may be starved of fuel, indicating a dirty carb. Also try having someone squeez the gas line primer bulb as you push the throttle forward. If it takes off then this indicates a fuel pump problem. Also try the Timing and Sync for inlines posted by Clams. This procedure works very well.