carburator rich/lean settings

[newDIYer]

1972 Mercrusier 140 I/0 with Rochester Carb.<br /><br />Rebuilt carb this winter still have the following problem.<br /><br />When cold starts great and runs great with Thermostatic choke rich/lean set in the middle. After engine warms up it is very hesitant(bogs down) at about 1100 RPMs. After nursing the throttle past 1200 RPMs she runs fine up to and including WOT. To solve the thottle up problem I have to rotate the rich/lean setting about 60 degrees counter clock wise (more RICH). This allows me to have good take off for sking etc... It seems to run fine at this setting when warm.<br /><br />When I go back the next day it floods on cold start and I have to set the choke back to the middle for cold starting. Then readjust to 60 degree position when engine warms.<br /><br />I'm open to any suggestions on how to solve this problem?

 

[akriverrat]

Re: carburator rich/lean settings

is the choke opening fully when engine warm? does choke cover have a wire going to it?

 

[newDIYer]

Re: carburator rich/lean settings

No wire to the choke. There is a copper tube that runs through the exhaust manifold to the choke spring housing. I assume this is to allow warm air from the manifold to heat the choke spring to let the choke open more when warm.<br /><br />By adjusting the choke to 60 degrees I am actually preventing the choke from opening as much. As the spring heats up and expands the choke is allowed to open more. This limits the air intake and forces a richer mix (I think as I am a novice on this subject). My problem seems to be that the choke is open too much when throttling up through 1100 RPMs and the engine bogs down and will even die if I don't compensate the throttle accordingly.

 

[Bondo]

Re: carburator rich/lean settings

The accellerator pump isn't pumping properly....<br />Fix it, then set the choke for Cold starts....

 

[newDIYer]

Re: carburator rich/lean settings

Thanks for the advice!<br /><br />I just rebuilt the carb and put in the pump that came with the kit. Any suggestions on what I may not have set right when I installed it?<br /><br />FYI, It was also doing this before I rebuilt the carb.<br /><br />Thanks again.