I just stumbled across this post while searching on VSS posts.I saw what Jerry posted about fuel pressure being 16-18 PSI for the 3.4 engine.Wouldn't that be a little high as the stock TBI runs from 9-13 PSI?I am running at 12 PSI constant as I have a pressure guage mounted under the hood , and another in the cab of the truck so I can watch my pressure due to an issue I had before with intermittant stalling , which turned out to be my fuel pump as I used a non EFI pump which couldn't handle the pressure and keep it constant.After swapping out the pump to an EFI pump , I had no more issues and the truck runs great with lots of power , being able to hit 107 MPH on the dyno , and I think it could have gone higher but the trans went into overdrive instead of staying in 3rd for the run.

Is there anyone else running a 3.4 with higher pressures?If so did you just modify the TBI to give a little more pressure or did you add a standalone regulator?I know the pump I have can handle up to 35 PSI constant with no problems , but its the TBI and regulator that cut it down to just under 13 PSI.I'm just curious on this as if the higher PSI would give me a little more performance, it might be worth looking into.The question is would the ECM handle the difference ok or would it complain and start throwing out different codes and problems.