If a 0.000000000002 micrometer rated filter has enough surface area it
will operate with LESS differential pressure than a small surface area
filter with 3 METERS pore size.

This is a vacuum pump ... meaning that it only has to deliver 15 psi
motive pressure plus about 2-3 feet of static head. A small dog can ****
harder than that.
The service advisory simply admits that Yanmar has a WEAK pump!!!!!!! A
pump that cant run against a 'dead-head'is cheap, ill designed, etc.

A clogged filter will always place stress on the pump. A filter begins
to become 'clogged' when approx 85% of its 'dirt capacity' is used, less
than that the pressure drop is linear, after that it rapidly accelerates
the rate of 'clogging' (becomes exponential) ..... thats why you NEED a
gauge to monitor it.