Mercarb question

[s.hadley81]

I have a 2bl Mercarb on my 1989 120hp and I was wondering if someone could explain to me what the stainless steel check ball with the spring under the Venturi cluster does. I've had a problem with flooding after I shut it down so i rebuilt the carb this winter and it was better but just last week it started the same thing again so i put in a new needle and seat. When I put the needle and seat in I cleaned it and noticed the spring under the Venturi had a nice twist in it so I put my old one in which was fine but I don't quite understand what the check ball and spring do. Also a little more info I did check fuel pump, sight tube and verify my fuel psi and all that's good. I'm gonna go put my carb back on in a day or so I'll know if I got it straight but just wanna know if the check ball coulda been playing a part . Thanks in advance for any help!

 

[alldodge]

The pic below is for a Rochester but the workings are the same. The ball below the accelerator pump allows fuel to come in but not out. The one under the venturi does the same thing. Accelerator pump sucks fuel in when throttle is released to idle, the venturi one keeps air from being sucked in. When throttle is opened the accelerator on closes off and allows the fuel to pass by the venturi one..

A leaking carb is either the valve needle and or seat, or the float is sinking. Can also be caused by a speck of crub

 

[s.hadley81]

Thanks alldodge that's exactly what I needed to know! I did weigh my float and that's ok so I was thinking maybe I got a crap rebuild kit and the needle or seat is my problem next time I'm gonna get a mercruiser one. After reading some old posts I found out the mounting gasket that came with the kit was to thin so I made one outta thick gasket material. After you explaining the check ball workings I think maybe the twisted spring I had could be why I had a very slight stumble on hard acceleration. Thanks again the help is much appreciated and I will post my results when I put my carb back on.

 

[s.hadley81]

The pic below is for a Rochester but the workings are the same. The ball below the accelerator pump allows fuel to come in but not out. The one under the venturi does the same thing. Accelerator pump sucks fuel in when throttle is released to idle, the venturi one keeps air from being sucked in. When throttle is opened the accelerator on closes off and allows the fuel to pass by the venturi one..

A leaking carb is either the valve needle and or seat, or the float is sinking. Can also be caused by a speck of crub

Hey alldodge,
I put my carb on and all is good so I have to thank you for the help. I got rid of the slight hesitation and the drip outta the venturis so I guess that kinked spring was my hesitation and a bad needle or seat was the flooding.I'm now just a bit smarter with your input thanks again I do really appreciate it.

 

[alldodge]

Your welcome, happy boating