Steven Shelikoff wrote:

Sounds like we have to limit this further. Ok, I'll limit it to the
typical filter, like a Racor fuel filter, with a typical pump, like the
Walbro, with the pump either before or after the Racor attached to it by
at least a few feet of hose and in both cases, a 3 psi difference
between the outlet and inlet. How would you explain a difference in the
performance of the filter media between the pump pushing or pulling the
fuel?

I did not claim there *is* a difference. As long as the DP is the
same, and fluid velocity is the same, there should be no
appreciable difference. I mean, if you continue to "limit this
further" such that all pneumatic parameters are identical,
operating in a steady state condition, then of course there's no
difference between suction and pressure filtration. There can't
be, QED.

The point I was making is that in real world applications,
parameters will not be identical, and the system is not steady
state. So you have to factor in the overall system design (pump
curves, filter cartridge design, flow rates, velocities, etc.) to
determine if there may be an impact, since the filter does *not*
operate independently of the overall system. For your basic
'rock-n-alligator' filters, I would not expect any differences.

And if I want maximum life out of the pump

You put a strainer in front of it.

You pick the parameters you want to maximize and go with it.

So true...

Keith Hughes