Well last week I thought I was having a nitrous related problem with my fuel pressure dipping down under WOT. Well today it happened again without using the nitrous. So far I've noticed this will only happen when I'm low on gas (1/4 or lower). My car idles at about 29-30psi and at WOT jumps to about 40-41psi. It doesn't seem to matter which gear I'm in once I stomp on the gas it jumps up to 40psi then once I hit about 4.5k rpms the fuel pressure will dip down to about 15psi, but If I have a full tank the fuel pressure stays at aroud 39-40 psi at WOT all though the rpms. anyoen have any idea of what would cause this or things I should check out?
Could be the fuel pump is just unable to pump the fuel at maximum pressure when the tank is low. You could always try keeping your fuel lines clean to maximize fuel flow and possibly upgrade your fuel lines with a steel fuel lines, which flow more fuel as well.