Originally Posted by nystateofmind27
Why would i need vacuum modulated bypass regulators and all this complicated stuff?
My goal is to use a walbro external 255 pump (electric) and take out the internal one. Any ideas?
because the original regulator is that type. and its not complicated... you will need a bypassing reg. on about every oem FI system with a return line. thats just how the system works. continuous flow. the primary advantage of this is prevntion/removal of percolated or boiling fuel in the lines and rails, thus avoiding vapor lock, or bogging from excees vapor in the lines.
most port type FI engines use vacuum modulated fuel pressure. at idle, light loads, and deceleration, manifold vac is high, and fuel pres. is reduced. under WOT, or heavy engine loads, or engine not running, manifold vac is low, or non existent, and fuel pres. is increased. this helps to broaden the injector`s operating range.
the factory ECM/PCM programming is tailored around modulated fuel pressure..
any reg. you use should also have this feature in order to match the original regulator`s performance, and keep fuel curves within the expected norms for the computer.
most (but not all) aftermarket bypassing regulators have the vac modulation feature.
an inline pump is fine, as long as you keep it mounted below, and behind the fuel tank, in order to to ensure easy self priming.
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