Simplest mechanism for increasing fuel pump pressure (while
simultaneously decreasing the volume available) is for the spring to
break. The shorter spring has a higher spring rate than the longer
(unbroken) spring and can increase the pressure up to double.
HTH,
Donald.
> From: "griffco" <griffco@griffco.ca>
> Date: Wed, 8 Oct 2003 07:53:34 -0600
>
> Nolan Penney said:
>
> > If the diaphragm were to stiffen with age, that could result in higher
> > pump pressures. Never seen that actually happen, but theoretically it's
> > possible.
>
> I wonder how this is possible? The diaphram is driven by the spring, which
> in turn is loaded (compresed) by the lever running on the cam. If the
> diaprhagm gets stiffer, the spring has less chance of moving or flexing it.
> The result is less fluid moved, either due to less movement of the
> diaprhagm, or due to the diaphragm moving slower on each stroke. Anyway,
> that's the way I see it. I've had diaphragms stiffen up to where they won't
> move at all.
>
> cheers, Fred
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