720 Idle issue

[Ol Blue 86 Nissan 720]

Can anyone tell me where on the carburetor I can find the fuel cut valve? My 720 shuts down on idle and I've been told to remove the plunger from the fuel cut valve. Thank you!

[datzenmike]

This can be caused by many things besides the idle cut solenoid. Check and see if it is working first. Have someone turn the ignition to on (not start) then off, on, off. If you listen near the carb you will hear a faint clicking sound, this is the solenoid opening and closing and it is presumed to be working. 

 

A vacuum leak on one of the many hoses can degrade idle quality and cause stalling.

A dirty EGR valve will leak exhaust into the intake at idle when it is supposed to be closed tightly. 

The calve clearance could be too tight on one or more valves which will drop the intake vacuum.

Timing may be retarded.

Idle speed not adjusted.

[ggzilla]

Probably a.small vacuum leak needs to be plugged.

 

[Ol Blue 86 Nissan 720]

Thanks to both of you guys. Gonna try to get to it this weekend. Just ran the truck 3 hours down the highway at 75 mph a few days ago perfectly. Carb had just been cleaned and idle screw set right on. Can't seem to find any vacuum leaks. Seems to get worse in heat.

[datzenmike]

Is it an automatic? There is a vacuum hose down to the transmission from the intake. Probably near the large hose to the brake booster. Speaking of which... maybe pull it off and seal up the manifold end to test it for a leak. Does it idle then?

 

Follow any hose connected to the intake. Maybe pinch closed with pliers and see if idle comes back.