What is the part number for this regulator?

[CLi87]

Hey all, i'm working on my 2000 Mercruiser 7.4 MPI and ran into a low fuel pressure condition, when I turn key on engine off pressure spikes to about 40 psi then drops down to 18 psi, with engine running at idle pressure is about 28 psi. I figure the fuel pressure regulator may have failed and I'm not too familiar with this vacuum based regulator system. From what I can see there's a fuel pressure regulator right above the fuel pump and a vacuum hose connected to it that goes to a T connector, one end of the T goes to the intake plenum and the other end goes to some sort of other regulator. I plan to replace both regulator but I can't seem to find the part # for the regulator off the T that's right next to the distributor in any parts diagram?

This is the diagram i'm using:

https://www.perfprotech.com/mercury-marine-parts-catalog/fuel-pump-and-fuel-cooler/assembly/2705/110?model=970

In the diagram it just shows B -> to fuel rail pressure regulator and I checked the diagram for the fuel rail/intake plenum and the regulator isn't shown on that diagram either?

 

[Scott Danforth]

test the regulator before trying to replace it.

test the fuel pump output by itself.

 

[CLi87]

How would you go about testing the regulator and fuel pump? I have the cool fuel system and the whole setup is in an assembly box that's real tight, not sure how I could get any connector in between the parts to test

 

[Scott Danforth]

The manual covers testing the regulator and pump. I would follow the manual