What should the fuel pressure be on the 5.7 tpi? The digital gauge on the car (my dads) reads constant 15, Is that correct?

 

Fuel pressure at idle 38-40 PSI is normal any thing less means problems.

 

Fuel pressure at idle with vacuum line disconnected and both sides of the hose plugged should read. 43.5 psi. That is stock fuel pressure

 

That is when you set the fuel pressure and not what it checks at idle.

 

then what should i look at? it raises up to 40 as the car shuts off, and the fuel pump and filters are new.

 

What is the fuel pressure at Idle and does it hold at Idle??? What do you mean "it raises up to 40"???

 

I had a fuel reg go out on me on my vert right after I got it.

 

Where is the fuel regulator at?

 

Right side under the TPI runners...It looks like a TOP HAT.

 

Yes, with a row of rivets around it and a vacuum port on the backside of the fuel rail.

 

This is actually my car he is speaking of. I have constant 25psi fuel pressure running. When I first turn the key on, I have 43psi, it stays steady 25 while running and idleing. Seems to run fine, lots of power.
on the flip side, this engine has been rebuilt and bored .030 over.
We are going by the fuel pressure on a electronic digital guage, and not for sure if that is the actual pressure, without connecting a fuel pressure guage.