Quote:
Originally Posted by MineralF30
Basically, the pump in the tank is the LPFP (low pressure fuel pump) and the one in the engine bay is the HPFP.
I had similar codes relating to fuel pressure for months and it ended up being my Walbro 450 LPFP. I did replace my HPFP before that and it didn't fix it, so I'd say replace the pump in the tank first and see if that fixes it.
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Well I logged my car with the JB4 and for my Low Pressure Pump, I'm basically reading nothing. So I am assuming nothing or not enough is getting delivered to the High Pressure Pump.
According to JB4,
FP L: Fuel pressure, low system. Pressure is read on the left hand scale X 10. Otherwise known as the in tank low pressure fuel pump. This value typically ranges from 55-70psi. If dropping below 50psi it indicates a problem with your low fuel pressure pump. Most often that problem is it needs to be augmented with an inline pump to keep up with the higher fuel demands required by ethanol usage.
FP H: Fuel pressure, high system. Otherwise known as the high pressure pump. Note all N54 include this and other platforms can only log this if also equipped with the flex fuel connector. This value represents the voltage of the high pressure 0-5V sensor, where a value of 20 is 5v. Each unit of measure is roughly equal to 150psi. Typical values at full throttle are 10-14, or 1500 to 2100psi. Values of less than 900psi as full throttle indicate a fuel delivery problem and the JB4 will failsafe at 700psi at full throttle. Note when not at full throttle a typical value is 5 or 750psi.