To do a static test (engine off) will need a source of vacuum (mity-vac) and a source of pressure (air compressor). Hot wire the fuel pump so that it is running.
The fuel pressure at this point is the basic set-point, same as engine running, vac line off.
Apply a vacuum source (mity-vac) to the port on the FPR. As vacuum is applied the fuel pressure should reduce 1 for 1 to the vacuum pressure. That is in psi. As most vacuum gauges are read in inches of mercury (Hg), will need to convert the units (google works for this).
On the other side of things, boost, apply pressure to the FPR port. In this case the fuel pressure should increase 1 for 1 as the pressure on the FPR port increases.
An example using round numbers: 40 psi with the FPR port open. Apply 10 psi to the FPR port. Fuel pressure should be 40 + 10 for 50 psi.
Note that this test does not check for fuel delivery with a running engine. Just that the regulator tracks correctly. And it does depend upon the fuel pump being able to deliver the required pressure.
If the pump is bad and can't supply any fuel at 45 psi, then this test will show that. It doesn't mean that the regulator is bad. In this case if the return line can be closed off and the fuel pressure doesn't increase, then we/you/I know that it is a fuel delivery issue, not a FPR issue.
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