I'm getting a code 44 (lean exhaust). I checked my fuel pressure by attaching the gauge and taping it to the rear window. My brother watched it while i dove the car around a little bit. When I step on it, it drops to about 20 and goes up when I let go. The gauge would reflect all the throttle modulations I would do by dropping when I gave it throttle and going back up when I let go. Is that normal?

No, it's not supposed to be constant. The fuel pressure regulator works on manifold vacuum, and it is supposed to be high with no vacuum (WOT) and low with full vacuum (idle). If you remove the vacuum connection on top of it, you should have about 43psi on the gauge. Sounds like you may have a bad regulator.

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[This message has been edited by crazyd (edited 08-03-2009).]

I haven't enough experience in these cars yet,but I would say pump.
There is a minimum spec for fuel pressure,and I think it is around 30psi.
Depending on load and rpm it will flucuate to the maximum spec.
The regulator will adjust pressure as needed,but the pump should be supplying maximum pressure available.
It should never drop below minimum spec.
A failproof test I use for them is 1st gear till redline,at the high RPM alot of volume is needed at that high pressure.
A failing pump will dip below spec during a run like that (or high rpm/high load) I only have to see it drop once for a millisecond for me to replace the pump and filter.
Alway's replace the filter with the pump even if it's very new. The new pumps will fail quickly due to a restricted filter,the old ones (not pwm) aren't as susceptible but it's good practice and 10$.

Hope this helps,
Def.

quote Originally posted by crazyd: No, it's not supposed to be constant.

Did you mean to say? "it's supposed to be constant"

What yr/engine do you have? Check the vacume
line that goes to the fuel pressure regulator. If it has
a leak it could cause low fuel pressure. On my
88GT this line also goes to the MAP sensoe so
a leak could also cause the MAP sensor to not
get the right manifold air pressure.

L4... No Vacuum to Fuel Regulator. It is almost constant and idle it 9-13 psi.

V6... It vacuum to Fuel Regulator.
Test at Schrader ...
Ignition switch on, engine Not running = 40.5-47 psi
Idle = 30.5-44 psi
Fuel pump= 60 psi Min. "With fuel return line briefly restricted." Mean you pinch the return and not any longer that needing. You can wrench the pump.

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[This message has been edited by theogre (edited 08-04-2009).]