Filter King

No, we’re not talking cigarettes here.

Filter King, made by Malpassi in Italy, is a brand of old(er) fashioned fuel filters with built in regulators.

For those of you who like a mental image to accompany your text, think something similar to an IV bag on a hanger, but smaller, in metal and glass, and with a filter inside the glass.

Apparently the slightest hint of H2O in the gasoline is enough to start corroding the fiddly bits where the actual regulator mechanism lives, eventually causing the 2.5 psi the Weber 42 DCNF need to run perfectly to rise (thus far) to 6.5 psi (and beyond?), which will overflow the carburetor floats and flood gasoline down into the cylinder intakes. Needless to say, not only will the engine not run well, there is a real risk of fire.

And you thought the car got horrible milage to begin with….

The fuel pressure gauge I installed between regulator and carbs (“not for permanent installation”, although it wasn’t specified whether it was the heat from the engine that could melt the fragile plastic part, or rather that gasoline that would melt through the innards before sending them, half liquified, towards the carburetors) showed a perfect 2.5 psi, regardless of pump used (the QP3 has dual, or redundant fuel pumps. Maybe a carry over from the earlier days when many Maserati models had dual fuel tanks, and a pump for each, or perhaps a nod to the aircraft industry and safety, but probably just an acknowledgement of the fact that they have a tendency to fail).

Trolling the web I’ve found more than a few regulators, and have been recommended to go with the 85mm size, even though Maserati outfitted these cars with the 67mm model as standard. More filter area, and a greater reserve for a very thirsty engine. The mounting holes and bracket are the same.