1985 720 What Is This Part?

[Rectangle720]

What the pick is pointing to on back of carb next to choke connecting rod. On my truck it doesn’t seem to do anything. Is it supposed to be connected to something?

[Sephakrid]

I think that's the lever for the choke pull-off. Apply a vacuum to the small diaphragm (silver can with a single vacuum line on the side) at the top of the carb and see if the lever moves.

[ttyR2]

Looks like a stop, of sorts, for the choke lever. The spring is looped around it, but doesn't actually have any effect on it. The spring is pushing on the choke shaft lever. I wouldn't think a manufacturer would ever let a steel lever use the aluminum carb body as a stop...it'd wear rapidly.

[datzenmike]

That is part of the choke un-loader or pull off. When choke is on and performance is needed it will move towards the camera and engage and push the other part forcing the choke open.

 

pulled off

 

 

There's a piece of linkage missing going down to the fast idle cam. It starts here...

 

Goes down behind the idle cut solenoid...

 

The plastic thing is the fast idle cam. It has a series of steps that prevent the throttle from closing to idle and revs the engine when the choke is on. It will run like shit with the choke on without it.

[Rectangle720]

Thanks Datzenmike. Does that sound like why I’m getting sputtering/loss of power at low rpm once the engine has warmed up?

[None_zero]

I'd say yes probably. You may notice if you adjust the choke from lean to rich and back you should be able to affect the resting position. Of that lever while the engine is cold. If it behaves the way mine does when the engine is warm that lever hangs limp because the choke is fully open 

[Rectangle720]

Thanks. My pull off is a bit different in configuration to what Datzenmike posted but does seem to be my issue. The choke pull off valve isn’t connected to the lever. There was a piece of what looked like bailing wire slotted in the plastic end of the valve creating a “bar” to push on the lever. I can’t find anywhere what the proper linkage is supposed to be. Any ideas are greatly appreciated.

[datzenmike]

Again, you are missing a rod that descends to pull the fast idle cam into place when the choke is on. Without this the engine will idle over rich and too slow. The fast idle cam holds the throttle open allowing more air in to match the extra rich mixture allowing the engine to rev at 1,800-2,200 RPMs when cold. This makes the engine warm faster and run better when cold.

[Rectangle720]

I hear what you’re saying, and there is definitely a possibility my inexperience is clouding my understanding, but the pictures you’ve posted and the symptoms you’re describing do not look or sound like what I’m dealing with. When warm, the truck is idling fast and running lean.

I have a piece of linkage going from the pull off lever (for lack of a better term) back towards the drivers side of the carb and is supposed to connect to the pull off valve but the connection has been compromised.

I see nowhere for linkage to attach to that lever and run down to the fast idle cam. I found this today and number 22 on the diagram below is what I’m looking at, and that rod is not connected to the valve.

[datzenmike]

The choke pull off only is needed when the choke is on and throttle is floored and needs maximum power. The pull off pulls the choke open allowing this. If the engine is warmed up the choke should be off and not of this will matter.