3.0 Carb (idle valve)

[mmarincic]

Quick Question

mercruiser 3.0 , merd carb

What is wrong when the idle needle dosen't do anything. Won't lean out when screwed in or get richer when screwed out.


Thanks

 

[ziggy]

Re: 3.0 Carb (idle valve)

are the throttle plates are open at all? idle mix screws don't do anything other than at idle. when the throttle plates are closed. if the throttle plate is open at all, the idle circuit in the carb is inop. including the mix screw.....

 

[Don S]

Re: 3.0 Carb (idle valve)

Not exactly there Ziggy. They are open slightly, what do you think that idle speed adjustment screw does? It opens the throttle plates.
On outboards, they are fully closed, but if you look they also have a hole in them to allow more air than the mixture screws can give.
I think MM has carb problems or an air leak.

 

[mmarincic]

Re: 3.0 Carb (idle valve)

Thanks guys: I'll check it out again this morning, hope I can get it right.
Going to lake Powell tonight and need it running