I need help understanding why this is happening (fuel pressure)
Ok so I have been watching my fuel pressure gauge since I installed it back in July. I've noticed that in a certain gear the pressure would always drop more than it does in others. Today I finally did some investigative work and this is what I found:
At idle the fuel pressure is 65-70psi. Upon spirited driving the pressure may drop to 60psi. Nothing to be alarmed about. Here is the interesting part. At WOT the pressure maintains a rock solid 60psi in gears 1, 2, and 3. Upon shifting into 5th, the pressure will begin drop rapidly. At around 3,000RPM it starts to drop to about 55psi and at 3,300RPM it is at 50psi. Anything beyond 3,500 and I'm well below 40psi. I actually saw the pressure drop to 20psi a few days ago with the engine running at ~3,800 RPM. I first noticed this when I installed my gauge back in July and found that I always had to feather the throttle in 5th to maintain atleast 50psi. Once it's in 6th gear and with the TC locked the fuel pressure problems go away.
So what I'm wondering, is there anyway to cure this without going to a full aftermarket fuel system? Before anyone says it, the fuel filters were replaced ~1,000 miles ago. I am just amazed that the pressure is ok in 1-3 and 6th but upon the selection of 5th is there really that much more demand for fuel?
Sorry for the long winded post. I'm just trying to figure out what is going on with my fuel system.