Just a question I thought I might ask. I have 2 ,93s. One had the pump rebuilt. I have noticed the smoke screw has about 1/4 inch of meat showing to go down with. The other still has the red marker paint and has not been touched I think. The screw is down flush with the nut, if turned in you would not have much to tighten the lock nut with. It does not smoke at all. I noticed this caise I was gonna crank it down a couple turns. The truck is kinda doggy, what if it was turned down by someone and set to look like it was untouched? massive smoke??

 

The smoke screw serves only one real purpose.... to apply some preload to the AFC diaphram. This preload will give the engine a "shot" of fuel to help with getting the turbo spooling... kinda like a helper with the first 50' of "launch".
After that, it's out of the picture.
If the truck is sluggish across the board you need to adjust some other things.
First, please, make sure you some gauges. You need to at least have some baseline readings before you go cranking on screws and *****....

I would remove the AFC cover, then pull the AFC rubber diaphram out. Clean it up real good. While it is out, look down the hole it came out of and cycle the throttle slowly to WOT. You should see a pin (guide pin) pop out of a hole toward the firewall end of the AFC hole. This pin should pop out cleanly and crisply.
It rides up and down on the "cone" attached to the end of the AFC assembly.
Look at the cone you cleaned up...do you see a "witness mark" on the cone were the pin has been rubbing???
Look again at the cone,,,,you'll see that there is an offset to the cone. If you turn the cone so that the deepest portion of the cone is facing forward (toward the hole were the pin comes out) you will be increasing the fueling rate per pound of boost. That will give a nice shot in the arm to performance.

Try that for starters... but get gauges..

pastor bob.

 

The pin that pops out and rides on the AFC eccentric controls a stop inside the pump that determines the maximum amount of fuel delivered per pump stroke (injection). The further "out" the pin extends, the more fuel can be injected.

In addaiton to this pin, fuel/stroke is also affected by the "fuel screw" on the back of the pump, which adjusts an internal pivot.

The stock pump should be set up to deliver a specific amount of fuel/stroke with no manifold pressure. Using the AFC alone, there are two ways of adjusting this "no boost" level: 1) Rotating the AFC eccentric, so that a deeper portion is facing the fuel pin 2) screwing in the "smoke screw".

I would guess that the two pumps you have were set up with the AFC eccentrics in different positions, though they may have just had different "fuel screw" settings. The second truck might be a dog because you aren't getting much additional fueling as the boost comes up -- if the smoke screw is cranked down to get enough fuel under no-boost conditions, then there isn't much eccentric travel left to add more fuel as the boost increases . . .

Does that make sense?