Varying neutral RPM... too much fuel in mixture?

[jheathco]

I've got a 5.7L Mercruiser that starts relatively fine, but has a varying idle RPM in neutral (it seems to slowly increase over time). After a few minutes, it will tend to either decrease RPMs to the point that the engine dies, or increase to the point where I have to turn the engine off (2k+).

The mixture seems to also be burning a bit rich.

The mechanic has rebuilt the carb twice now to no avail. He thinks a new carb is in order - any other thoughts before I go down this road?

 

[180shabah]

Re: Varying neutral RPM... too much fuel in mixture?

Did your mechanic test fuel pressure, adjust the float level, set idle mixture, adjust the choke etc, or just clean it up and put it back on?

Do you have a vacuum gauge you can hook up?

 

[Bondo]

Re: Varying neutral RPM... too much fuel in mixture?

I've got a 5.7L Mercruiser

Ayuh,... Could ya narrow that down abit,..??.. Vintage,..?? 2bbl., or 4bbl.,..??

 

[Don S]

Re: Varying neutral RPM... too much fuel in mixture?

Come on Bond-o, you know that nothing on a 5.7 has changed since the late 60's

 

[Bondo]

Re: Varying neutral RPM... too much fuel in mixture?

Come on Bond-o, you know that nothing on a 5.7 has changed since the late 60's

Ayuh,... And they only bolted on 1 carb too,.... I forget sometimes,...