I'm a little confused on the location of the TBI fuel pressure gauge. It appears that the gauge is typically installed in the fuel inlet line before the throttle body and therefore before the pressure regulator. It seems that you would want to check the pressure after the regulator and before the injectors which then seems difficult with the TBI setup.

I'm also assuming that the fuel pump is always putting out more pressure than necessary and that the pressure regulator reduces fuel pressure as required.

So if your gauge is before the regulator, how do you adjust and know what the injector pressure is? Am I misunderstanding something? Thanks for any help / explainations.

I think it all breaks down to one of those (I should remember this from physics calss) issues.
The pump puts out lots of pressure. The regulator lets a lot of the fuel back to the tank.
once the fuel enters the injector pod the only way out is the injectors or the regulator.
so in theory the pressure at any point after the fuel pump to the regulator should be the same as on the injectors.
the fuel used by the injectors is compensated for by the fact that the pump always puts out more than the injectors need.
I just switched from a TPI setup running 45psi to a TBI that now runs 17psi. all I did was run the fuel lines to the TBI and the regulator on the TBI did the rest.

It's best to consider the regulator as a pressure relief. Everything upstream from the regulator is determined by the pressure setting. Everything downstream from the regulator is not pressurized. Not like an air line regulator which sets pressure for everything downstream from it.

Hey PaulD how did you cut the front springs?
How much did it lower your car?
Did it change the ride on your car?

I cut 3/4 coil off the front springs. The police package springs are quite high. The Impala rear springs kept the rake the same. I forget how much it lowered everything but I'd say at least 1 1/2".

Thanks for the replies..... I think that makes sense now. I was thinking of it more like an air pressure regulator. It's really more like a waste gate for a turbo set up. It takes the pressure it needs for the injectors and dumps the rest back to the return line.

Thanks again.