Adding Racor 120 or 400 Series to Yanmar 4JH4-HTE

[GravityCoaches]

Our current setup has a Racor 500MA between the tank and the Yanmar filter which is fitted to the engine. (I am intentionally avoiding using the terms primary and secondary to avoid opening a semantic can of worms).

We use 30 micron filters in the Racor 500MA.

Due to previous issues with dirty fuel, I would like to add an additional filter between the two, along with the necessary valves to bypass the first should it become clogged.

My intention was to install an additional 500MA, but due to space limitations, a filter with a smaller body would be much easier to install.

I am looking at the Racor 120RMAM, a spin-on, 15 gallon per hour, with a maximum allowable pressure of 7 PSI. Yanmar seems to indicate that the fuel pressure generated by the pump will only be 2.9 PSI, and I am making the assumption that the GPH rating indicates the amount of fuel the engine actually draws rather than a general time in service rating for the filter.

The 400 series is also a possibility, with 45 or 60 GPH available, and 15 PSI allowable.

The smaller size and dual inlets/outlets make these attractive to me, but I wonder if I am missing something basic in going with these smaller units.

I have room to install the 500MA if I add several feet of fuel line and install the new filter 2 feet above the horizontal plane of the engine/fuel tank, but I am worried that is less than optimal as well.

Any thoughts are appreciated.