Hi

I have converted my Mercruiser 350 Mag MPI to a fuel return line system.

The original dead end fuel line system has two pressure reluators (one at the pump/fuel cooler and one in the fuel rail).
As I am using the original return line coming from the fuel rail now, I need to use the regulator in the fuel rail which was previously superseeded by the pressure provided by the one in the fuel cooler.

Does anybody know what the fuel pressure of the fuel rail regulator is OR where to get a 43 psi fuel pressure regulator from which fits the fuel rail, so it matches the original pressure regulator to prevent the engine from running too lean or rich?

Fuel cooler fuel pressure regulator: 861126A1
Fuel rail pressure regulator PN: 885174

Many thanks
Martin

Not familiar with 350mag fuel system, but look for an aftermarket adjustable regulator.

Many of those bosch type fuel rail regulators have their rated psi embossed on them.

As example, see this one.
https://nuwavemarine.com/uncategoriz...CABEgJdIvD_BwE

And yes, 300kpa = 43.5psi

If its like the one SB shows, then its mid 90's GM LT1 stuff and probably available at a foreign auto parts store (in Germany haha). Here is a Bosch one like above for a 95 Corvette:

https://www.summitracing.com/parts/b...EaAiyYEALw_wcB