Rebuilt carb, same problem

[nola mike]

Re: Rebuilt carb, same problem

An air leak affects the IDLE speed/mixture more than anything else.

The higher the manifold vacuum (idle/cruise) the more effect the leak will have. A leak is essentially imperceptible at open throttle.

yeah, i was thinking that since i don't have symptoms at higher rpms. but my idle is fine, so i guess that probably isn't it. do you still think it has to be the AP circuit? why do i have problems starting with the throttle open if that's the case?

 

[Aloysius]

Re: Rebuilt carb, same problem

A low float level can cause a flat spot in the "transition" circuit. At about 1500 rpms the carb transitions from the idle circuit to the main metering circuit. This transition point is affected by float level and air correction jetting.

The accelerator circuit only works when the throttle is moved, forcing the pump piston to move. Just because it pumps some gas when the throttle is opened fully doesn't mean the quantity or especially the DURATION of the pump shot is correct.

 

[nola mike]

Re: Rebuilt carb, same problem

Well, to resurrect a way old thread...
Warm weather got me working on the boat. I took this carb out, and took it apart. Noticed that the float level and/or drop were off. Not sure which. From the instructions that came with the kit, looks like the drop/level is measured from the gasket to the farthest dot on the float. The merc manual says the opposite. On my rebuild, it appears that I compromised and measure one to the near surface, and one to the far surface. So hopefully this is my problem. Which is the correct measurement? I left my grease gun behind, so was unable to grease the gimble bearing, reinstall the lower, and start her up today...boo.