RE return to fuel tank

[Steve]

Lots of stuf snipped

>I agree completely with what you say, Roy, BUT:
>
>I still maintain that combining a pwm control of voltage to pump (which
>follows an engine load/speed matrix) with a conventional regulator and
>return line would work better still. More complicated, yes, but better pump
>life and better pressure control would both result.

Thats exactly how Nissan does their fuel pump control on high output cars.
Another consideration for passenger cars is fuel pump noise.  By controlling
the voltage you can reduce the fuel pump noise at idle and low rpm where
high
 output is not needed.


>Next step one should
>consider is the idea of putting float vents on the (tops) of the fuel rails
>so as to make absolutely sure that no vapor ever collects in them or gets
>fed into an injector. If one chooses to go with a two (pressure) stage fuel
>system (best of all), a positve displacement, gear type mechanical pump is
>well worth considering (the  volume of fuel available from one of these
>will track engine speed with no further ado, plus you lose a large chunk of
>electrical overhead by going this way. Drives for such pumps are
>commercially available, as are gear type pumps which are hard anodized and
>coated with appropriate polymers on the inside parts.
>
>How much of this stuff you do all depends upon the sincerity of your need
>for speed, and upon how much you have invested in your engine, as well as
>upon how much you are willing to spend to protect your investment--sorta
>like buying insurance, only more fun.
>
>Regards, Greg
>
>
>

Steve