Rough cold idle 3.0 mercruiser.

[Juel-dk]

Hi All

When i start my mercruiser 3.0 from 1993, it has a very rought idle, but after a while when its warmer, it idles like new!!
I pulled the plugs today, and they where all black, not from oil, but to rich mixture i guess.
Some times when i open to full throttle from idle, it stalls a littlebit..
What do you guys think i should look for ?

Kind regards
Morten

 

[Haut Medoc]

Re: Rough cold idle 3.0 mercruiser.

I'd check to see if the choke is operating properly.......​

 

[Juel-dk]

Re: Rough cold idle 3.0 mercruiser.

I'd check to see if the choke is operating properly.......​

Super, that was my first idea also, i just wanted a 2. opinion

Thanks for the answer

Kind regards
Morten

 

[frank suppa]

Re: Rough cold idle 3.0 mercruiser.

if your carb has an automatic choke it will also have a choke pull off as soon as motor starts (cold start only)choke pull off will open choke butterfly about 1/4 inch, enough so engine can high idle an not overload,choke pull off is usually a vacume diaphram externally mounted.pod easly replaced.

 

[rodbolt]

Re: Rough cold idle 3.0 mercruiser.

3.0 uses an electric choke heater. and it does take a bit to heat it and pull it off. in the meantime learn how to start it at about 1500 rpm and monitor the throttle while its warming up.