Carb adjustments

[Jsiples]

This is a Merc 3.0 I4 with conventional ign. I had my father-in-law the brilliant mechanic decide to put his two cents in on my motor while I was gone and now the mixture and idle is all messed up. Could someone let me know a place to start to get it back in the right parameters. It is a Rochester 2BBL.

 

[freelunch]

Re: Carb adjustments

Hey try searching, I have the same carb and know theres alot of info on this subject out there.

 

[Bondo]

Re: Carb adjustments

Mixture Screw starts at about 1,1/4 to 1, 1/2 turns out,+ is adjusted to Best Idle from there.....

Idle is set to 650/700rpms.......

 

[Jsiples]

Re: Carb adjustments

Much appreciated got it dialed in was running like a champ over the weekend other than one item . Quick question regarding the idle speed?? When I start from cold and let it run up to operating temp it sits just where it should 650-700. When I idle in forward same thing. When I make a run for 10-15 minutes and then come back to forward idle it will not return to the original idle I mean it sits around 12 to 1300, and this is not just for a few minutes it will not idle down unless I turn off the boat and restart?? Not an expert here, just is hard and I know terrible to shift like that since it is bad on the drive any suggestions or recommendations? I thought battery, but it is pretty much right in the middle where it should be prior to the run and after.

 

[Coors]

Re: Carb adjustments

your throttle cable needs cleaning or replaced. when it is idled high, see if you can open the hood, and manually pull the cable back to idle; either the cable or the carb, probably the cable.

 

[bjcsc]

Re: Carb adjustments

Make sure the linkage to your secondary (and in general) is adjusted right and not binding up. Your symptoms can be caused by the secondary plate sticking open a bit. When you're restarting, the cycling on the linkage could be freeing it up, but once you use it (the secondary), it could be sticking...

 

[ziggy]

Re: Carb adjustments

when she's idleing high after yer run. go back and see if the throttle plates are closed after ya come back to idle. i have simialar problem and it's my throttle plates that aint closeing far engough.

 

[Jsiples]

Re: Carb adjustments

Appreciate the input makes sense to me, it hasn't been replaced since I have owned it. I hope it's not the carb I just had it rebuilt last summer.