I've done a search, but can anyone quickly explain how our fuel system works?

I understand we have a high/low system (>25% throttle = high pressure), but I'm a bit confused as to how the regulator fits into the equation. I jumped my fuel relay (with the engine off) and the fuel pressure stayed around 60 no matter what vacuum I pulled on the regulator.

What am I missing? When does the regulator come into play?
Coldie

 

the regulator's job is to keep the pressure drop across the fuel injector steady. (stock is 39 psi) it adds pressure when boost is present in the intake, and removes some when there is vacuum in the intake. when you jump the resistor at idle, the pumps are flowing more than the return line can handle, so the fuel pressure creeps up because not very much fuel is going into the motor. fuel demands at idle and at 5500 rpms at wot with lots of boost are vastly different.

 

So that's what I would expect, but when I jumped the resistor (with the fuel pumps on and the truck off) and pulled full vaccuum on the regulator, I was at about 54psi.

Is the return line really that small? (I didn't try messing with the regulator when the pumps were on their low setting, maybe that was my issue).

Does the regulator actually increase fuel flow when boost is detected, or is max flow at ambient pressure?

Coldie

 

Hayden, that doesnt surprise me the fuel pressure spiking up like that with no demand on from the injectors and the pumps cranked up. Your right the FPR is not large enough on the return to relieve enough pressure, Also, the regulator will increase fuel pressure within the rail during boost as well as reduce FP accordingly while in vacuum in attempt to keep the effective FP in the 39-40psi range, remember at 10 psi of boost that pressure is exerted on the opening of the fuel injector when it is opened therefore you should see approx. 50psi FP at the rail.
Come to the get-together tommorow and we will have fun bench racing this issue.
Steve