Fuel Pump Roulette

phunk

^^ Correct, the fuel pump only primes when you tell it to, by turning the ignition to full ON without activating the engine starter. Otherwise the fuel pump relay is just energized basically at the same time the starter is activated.

The reason your car starts harder after upgrading the fuel pump is because you will now have a spike in fuel pressure at engine start and idle. The fuel pump module in a 370z uses regulator waste fuel to create a pressure differential in a pair of venturi action jet pumps for transferring fuel inside the tank. The orifices of these jet pumps behind the regulator outlet are "tuned" for the amount of waste fuel there is with the stock fuel pump. With a larger fuel pump, the amount of fuel passing through the regulator is much higher, and the orifices are too restrictive, and they backup the pressure regulator causing a fuel pressure spike. One of them can be removed, enlarged, and reinstalled to fix the pressure spike.

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