My current project involves making a variable rate fuel pressure regulator for a tbi system. I want the fuel pressure to sit at 9 to 13 when not in boost(stock), but have the ability to rise up to just under 30 in boost. (1:1 ratio)
I know the 94 95 454 TBI trucks were set to 30 PSI. I also know that the spring sets the maximum available fuel pressure. Is there a way I could use an oem 30 PSI fuel pressure regulator meant for the 454 on the throttle body of a 4.3 and have it run 9-13 PSI ubder nornal driving conditions but raise under boost?

 

Much better wording so you can make sence of my question. In reference to making a vacuum referenced fuel pressure regulator or in my case boost referenced, is there any way to use the 30 PSI regulator out of a 94-95 454 TBI in the oem throttle body to maintain 9-15psi in non boosted conditions, but then raise to 30 under boost? I understand after drilling the weld out, the further and I turn it the more the fuel pressure rises. Would it just be a matter of modifying the throttle body to access the bolt and then backing it out until I have 10 psi? I apologize but my last projects have been LS Motors and I am somewhat unfamiliar over with how base pressure is set on a TBI in factory form.

 

Yes...but...don't ruin the pressure regulator like I did. I guess I didn't drill far enough, (or too far) what ever I did wrong, when I tried to turn the screw, the whole screw assembly tore out of the housing. The thing is just crimped in place, and the crimp let go from the torque of turning the screw.

Probably not.

That is, you could achieve 10 psi if there's enough room in the housing to allow the spring to relax that far. I'm guessing there isn't. That's why GM used softer springs for lower pressure.

But since the housing that the spring sits in is vented, you'd have to fabricate a new, sealed housing that connects to manifold pressure. You could make the new housing a little longer, giving the spring more room to relax--but then you get a regulator that's very touchy. A tall, soft spring can allow the regulator relief valve to open and close with little change in the force applied by the spring. The regulated pressure stays very close to the "ideal". A short, stiff spring will change force more abruptly as the valve moves open and closed. Regulated pressure varies as the valve is forced farther open vs. closed.

Is the diaphragm for the pressure regulator different/stronger on the 30-psi applications? You wouldn't want to over-pressurize the rubber/fabric diaphragm. If you tear a hole in it, you have gasoline pouring into the spring chamber. The OEM chamber is vented, gasoline would spray onto the intake manifold. A sealed chamber would put gasoline into the vacuum/pressure hose and then into the inside of the manifold to be burned--a super-rich mixture.

Why are you making a pressure regulator when they're commercially available, with actual engineers doing the design work? You can't be the only guy wanting more pressure under boost.

Why are you starting with a 4.3L throttle body?