Here's the problem

After repeted tuning attempts at 40 PSI of fuel pressure, my car runs super rich after I put on the regular O2 sensor. with a wideband O2 it runs fine

when boosting i get copious amount of black smoke behind me that would make James Bond Proud, but thats not what I want.

This Morning I dropped the fuel pressure to 35 psi and the smoking and popping noticeably reduced (almost none). no detonation heard everything still runs great and less backfireing/popping at the muffler.

So...with my current setup, (see below) is it safe to run so little fuel pressure?
yes I know the right way to do it is with a wideband, but thats not an option now.

is it possible the Fuel pressure regulator isnt letting enough fuel return to the tank under boost?

any thought s are appreciated.

 

anyone?

 

what size of injectors?

 

RC 550's all specs in Sig. thanks