carb question please help!!

wildcat8466

Seaman
Joined
May 27, 2007
Messages
55
rebuilt carb 2bbl rochester, adjusted fuel air starts soon as you turn key. The problem is on cold start I turn the throttle on to set choke and when it starts it runs about 3500 to 4000 rpm until you mash the throttle to release the choke and it will idel down. but I kn ow this is not right. What is wrong ? Is the choke adjusted wrong because after it warms up it purrs at 900rpm but cold start is the problem, please help!!
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: carb question please help!!

What engine, what year, serial number?
 

wildcat8466

Seaman
Joined
May 27, 2007
Messages
55
Re: carb question please help!!

1989 3.0 mercruiser serial number don't know and the boat is up to the barn Is this enough info or do you need more??
 

Bondo

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Staff member
Joined
Apr 17, 2002
Messages
70,467
Re: carb question please help!!

rebuilt carb 2bbl rochester, adjusted fuel air starts soon as you turn key. The problem is on cold start I turn the throttle on to set choke and when it starts it runs about 3500 to 4000 rpm until you mash the throttle to release the choke and it will idel down. but I kn ow this is not right. What is wrong ? Is the choke adjusted wrong because after it warms up it purrs at 900rpm but cold start is the problem, please help!!

Ayuh,.. a 900 rpm idle is Way to high, should be 650/ 700 rpms...

My guess is yer choke Linkages are hangin' up somewhere...
Or,..
It's an automotive carb with the hi-idle steps in the linkage,..??...
 

mpdive

Chief Petty Officer
Joined
Apr 23, 2011
Messages
567
Re: carb question please help!!

Your choke should not be "sticking" because there is no "fast idle cam" on marine carbs. If it is an automobile carb I would replace it with a marine carb especially if it is not equipped with the fuel dump port for fuel pump failure. Also your base idle is too high. As bond-o said 650 750 would be more in line with specs. Check and see if you have a fast idle screw that sit's on a fast idle cam. If so your asking for problems tearing out your drive and possibly an accident at the dock.
 
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