Mercruiser 3.0L choke adjustment

[fourtwenty]

Recently had the carb repaired to fix a bog down condition under load related to the accelerator pump. Im having a hell of a time getting the choke adjusted properly. The engine runs really rough for the first few minutes until it warms up. I have to keep the rpms north of 2000 or it stalls out. It seems to be an issue with the choke plate not opening enough when cold. If I manually open the choke plate while its warming up it runs much better.
The choke adjustment range is pretty small. Can I continue to rotate the choke clockwise beyond the notches, until it gets to a point where it will allow enough air by to run smooth and not stall out?

Edit: 2001 bayliner 175

 

[Scott06]

Recently had the carb repaired to fix a bog down condition under load related to the accelerator pump. Im having a hell of a time getting the choke adjusted properly. The engine runs really rough for the first few minutes until it warms up. I have to keep the rpms north of 2000 or it stalls out. It seems to be an issue with the choke plate not opening enough when cold. If I manually open the choke plate while its warming up it runs much better.
The choke adjustment range is pretty small. Can I continue to rotate the choke clockwise beyond the notches, until it gets to a point where it will allow enough air by to run smooth and not stall out?

Edit: 2001 bayliner 175

you may need to bend the linkage to get it to the correct opening amount not just adjust the element which is more for the amount of time it stays closed.

Did they properly set the idle mix and speed ? In warm weather it should really not need much choke anyways if properly set up.

 

[Lou C]

There’s often a vacuum operated linkage that pulls the choke open a fraction of an inch (choke pull off) if the vacuum hose or the diaphragm leaks the choke won’t open a fraction of an inch like it should. Also a lot of people are unaware that on most engines (not sure about Merc TKS) with carbs you have to open the throttle all the way to allow the choke to close & set the fast idle speed by advancing the throttle about 1/4 or so. This will give you the fast idle you need to keep it running when the choke is still mostly closed (1200 rpm or so). Marine carbs do not have a fast idle cam like automotive carbs do.

 

[Scott06]

There’s often a vacuum operated linkage that pulls the choke open a fraction of an inch (choke pull off) if the vacuum hose or the diaphragm leaks the choke won’t open a fraction of an inch like it should. Also a lot of people are unaware that on most engines (not sure about Merc TKS) with carbs you have to open the throttle all the way to allow the choke to close & set the fast idle speed by advancing the throttle about 1/4 or so. This will give you the fast idle you need to keep it running when the choke is still mostly closed (1200 rpm or so). Marine carbs do not have a fast idle cam like automotive carbs do.

choke pull off on a mercarb is inside the choke element housing. Its a piston behind the element vs a separate diaphragm with hose like a qjet or divorced choke

to the op this like shows the adjustment of the choke by bending the linkage

 

[Lou C]

So they use a vacuum piston like Holley used to do....

 

[Scott06]

So they use a vacuum piston like Holley used to do....

The mercarb is a descendant of the rochester 2 jet so yes uses a vacuum piston in the choke element housing. Very similar to the holley electric chokes

 

[Lou C]

Yep it looks familiar to me we had a Rochester 2GV 2 bbl on our 1972 Chevy Impala 350.

 

[Scott06]

Yep it looks familiar to me we had a Rochester 2GV 2 bbl on our 1972 Chevy Impala 350.

I have also had several 2 jets-

grandfathers 1966 Penn yan merc 150 hp
1965 Lemans 326 2bbl
1965 GTO has 3 of them (tripower)
1991 Sea Ray - 3.0 had a mercarb

Only real difference I see is the mercarb has one mixture screw vs two.