Randy Jones wrote:
>
> Roman,
>
> Most of the EFI port injection engines (as opposed to "throttle body" type
> with a central injector) do vary the fuel pressure based on engine load
> (manifold vacuum).  A vacuum signal from the intake manifold is applied to
> the fuel pressure regulator diaphragm so the fuel pressure tracks with
> manifold vacuum.


Yes I know this. :o)
I should have been more specific and said it
"keeps a constant pressure with regard to the
manifold vacuum". The effect is that the injector
pulse length controls fuel amount. :o)

> Some newer systems are now using constant fuel pressure, and requiring the
> ECM to compensate the injector pulse width for the variation in intake
> manifold vacuum.

I haven't seen this type and not real keen to
see it either. :o)
-Roman

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