Is there a way to bench test the non-adjustable type fuel pressure regulator? I think these are only on the late model L-jet FI systems. It has the vacuum connection on it. I have a couple in a box I want to test to see if they're good.

I assume one test is that it doesn't leak to the vacuum port. What is the set point at atmospheric pressure? How is it supposed to respond to increasing vacuum?

I suppose you could do it but you would need to know the base vacuum.
Its a rising rate regulator.
Setup a fuel gauge , some fuel, and a vacuum source that you can increase slowly.

Rich

A suppose a faulty regulator would make for too rich mixture. The fuel pressure should be reduced as the the vacuum level of the engine increases. Correct?