I have the HSR intake with the adj fuel pressure reg. & Ive notice a serious rough running motor at about 3000 to redline in neutral or while driving. So I checked the fuel pressure while the car was idling & it was a solid 38lbs. As soon as I snapped the throttle back the pressure rose to 40lbs and then dropped down to 25-30ish & stayed there. I disconnected the the vacumn line & the fuel pressure rose to 45 lbs. With the vacumn line off the fuel pressure stays at 45lbs. no matter how fast the throttle is snapped open. Can u tell me "WHAT THE UCK is going on here!!
njdaewoo

 

If your fuel pressure drops with more throttle then your fuel system is insufficient due to a weak pump or some kind of obstruction. Unfortunately I can't tell you which it could be.

 

Thats normal. When there is no vaccum going to the regulator is stays at its max setting, that is why you set it with the vac. line off, so you can set its max pressure. The vaccum differences created by the engine revving arent reaching the regulator, so it won't change.
With the vac. line connected it will vary the psi depending on how much vaccum it gives the regulator. More vaccum will lower the pressure, while less vaccum will raise it, with no vaccum at all being the max psi you set.
Sounds like its working fine.