Quote:
Originally Posted by phunk
that is an example of a unhealthy fuel pressure curve. a side effect of upsetting the balance in the fuel pump module by putting a larger pump in without making the proper modifications to accommodate the much higher bypass fuel volume.
your fuel pump is overwhelming the regulator and/or venturi passages behind it. i am guessing you have larger than a 255lph in there to see as high as 72. the canister fill venturi on the bottom of the fuel pump module can be opened up a bit to bring your pressure back down. (this can serve as a reminder to me to work more on my (not-yet-so) "ultimate fuel pump" thread.
the pressure comes down when you start burning more of the fuel because there is less volume that the regulator has to relieve, and backed up pressure from the venturi blockages begins to lower
so the issues are correctable. if your A/Fs are staying inline, there is no immediate rush to resolve it.
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I'm running the 340lph. AFRs are pretty good. Closed loop I stay between 14.7-15.2. Open loop I'm mid 11's under load. It goes a little rich if I apply throttle a real low rpms (like being in 2nd under 1500 rpms and accelerate in traffic). It clears up almost immediately.
Since AFRs are pretty good I figured I would wait until the S1 upgrade. Will that fuel return setup completely fix my issues? Or will we need to discuss other fixes?