Carb Mixture Question

[72f100]

Just a quick question for you guys, hopefully somebody has an idea for me. I'm having a heck of time trying to tune my carb, I'm just not sure what the issue is. I've got a 72 f100 with a 302/3speed and a motorcraft 2100. In normal driving conditions, the truck is really happy when I run the fuel mixture screws about 1.5 turns out. However, if I pull up to a stoplight, it dies (starving for fuel). In order for the truck to maintain idle when stopping, the mixture screws need to be about 4 turns out. But when that's the case, the truck is a lot more rough on take off and the performance seems to suffer when driving. The carb has been through a rebuild and everything else is set properly (I believe). Any ideas where the problem might be?

[mljjones67]

Hows the condition of the fuel pump? I am wondering when you are in the lower rpms its not pumping enough fuel to keep it running. Just a thought.

[72f100]

The fuel pump is brand new and I didn't notice any change in performance when I replaced it.

[Wes]

1st thing check and adjust points and timing, then set rpm screw. Fine tune the idea fuel mixtures screws(highest rpm) readjust rpm screw after idle mixture screw adjust is complete. If those steps don't solve your problem check for vacuum leaks, and the float level.
Does this engine have an egr valve ? 72 might be a little early for one. If it does the egr may be sticking open when you to stop, creating a vacuum leak.