I have the walbro fuel pump installed on my 99 S/C max and i'm pretty sure its running rich. I want to know if i can lower my fuel pressure with just the S-AFC? Instead of buying both the SARD FPR and S-AFC, if not, then would I be ok running just the S-AFC for a little. I really want to dyno tune my car but money is a little tight and I'd rather just by the S-AFC for now. Thanks for any help

Nope, the S-AFC won't affect fuel pressure. You can use the SAFC to help adjust your a/f ratio, but you must spend time on the dyno to tune it. The afc adjust the amount of fuel being delivered, not the pressure it is delivered at. An aftermarket fpr would be a lot cheaper than buying a safc and the associated dyno time. Hope this helps.

Yes that definitely helps, thanks

No you use the SAFC to add fuel(richen fuel mixture) or subtract(lean) fuel mixture. You use the Vortech FMU to adjust fuel pressure by changing discs, or you can adjust it with that SARD or Cartech FMU.

Just a footnote to add to what you're correctly saying, the SAFC adds or subtracts fuel by controlling injector pulse width.

A question I have (sorry to ***** up your post, but it's related) is does the SAFC affect afr during partial throttle acceleration when the ecu is in closed loop mode and is making adjustments based on oxygen sensor input? I'm thinking it does, but I remember reading about some doubts about this.

Nope. The SAFC can only be set to work above 50% throttle, or else the ECU will eventually cancel it out. Kinda sucks.

39% throttle

Not sure what you're saying here.

The SAFC should be set to work above 39% throttle, not necessarily 50%.

Oh, that's right, I forgot. I had a senior citizen moment, I guess.