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So the 96-99 Fuel system has a returnless >fuel line, only one line leading to the rail. So the FMU >taps into this line and restricts the flow to the rail, >increasing pressure right?
Well, that's how STAR sort of has it done. But no, most HRC users have the SFMU tapping into the fuel line that LEAVES the fuel rail(the test port) and heads back to the fuel tank. By doing so, it causes pressure to BUILD in the fuel rail to whatever pressure is needed to make the car idle according to specification AND force the fuel injectors to become "bigger" by having more fuel pushed out due to the increased fuel pressures in the rail. Therefore, the fuel inlet line stays exactly the same.
But you're right about the 96-99 fuel systems having a RETURNLESS fuel system. That's why it's necessary to ADD a fuel return line to bleed the excess fuel after the pressure back to the fuel tank. That's how stock turbo cars work, and that's the optimal setup for your car.
Now, as I have repeatedly criticized before, the STAR system has you adding the standard FMU at the rear of a 96-99 fuel system where the stock FPR sits, and run a vacuum line to the back of the car thereby causing the same effect of increased fuel pressures throughout the entire fuel line and inlet. That seems a little weirder to me though, and I don't recommend it, especially given the length of vacuum line requried to message the FMU to increase fuel pressures during boost. Basically, it becomes the fragile "lifeline" of the car during boosted operations.
But doesn't this restrict the >flow to the injectors?
Not if it's done according to the HRC method, by ADDING a fuel return line. Otherwise, you're right, it does RESTRICT flow TO the injectors, but at the same time, it INCREASES fuel pressure. But that's the concept of the newer innovative and more emissions friendly returnless fuel systems you see everywhere.
_____________________________________ Jason ESi-T
04' BMW 325Ci 91' Nissan 240SX 98' Eagle Talon ESi (sold)
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