305 won’t turn off

[smf]

I have a Grand Prix with the 305 that sat for quite awhile. It starts right up but it’s sputtering before shutting down. It also seems to be idling high when running. I tried running quality gas and tec Ron through it with no results. Any idea how to fix this? It only has 30k on it

 

[Bonnewagon]

A high idle means the carb is adjusted wrong or there is a vacuum leak. That leaves the throttle open too much or it is getting excess fresh air and allows the engine to "run-on" after the ignition is shut off. Check for vacuum leaks. While running adjust the idle down to where it should be, around 650-850 rpm. My guess is it won't idle well down that low and someone adjusted it up to where it is out of the idle circuit. It probably could use a good carb rebuild.

 

[DRIVEN]

Could just need the choke linkage hosed down. Fast idle cam might be grimey.

 

[McGillicutty]

I had similar issues a year ago after it sat for six months. The throttle link was sticking open, maybe some other things too. I cleaned up everything that moves on the outside of the carb and it has been running smoothly ever since.