I have a 1993 Z28 that was getting dyno tuned by ION today. He was
getting great numbers from it becuase the PCMFORLESS tune was way
too lean. However, when getting about 3K rpms, the car would stay
lean. We hooked up a fuel gauge to the rail and the pump fell to
about 20-25 PSI of pressure about 5500 Rpms. It was set at 45 PSI.
This is the fuel system - racetronix intank pump with hotwire
harness, 30#SVO's, Aeromotive regulator, brand new Delco fuel
filter. Everything is about 3,000 miles old. This is on a 1993 Z28
with a CC306 and LLoyd heads. I checked the ground, the wiring
harness and checked all lines for damage or kinks and found
nothing. I have installed quite a few pumps in these car so the
installation should not be and issue.
I am lost and have to get it fixed within 1 weeks before ION comes
back
to
hopefully finish the tune. This is a copy of my post on Camaroz28.com

So I did this-

I put in a new pump becuase racetronix said that is what the problem is after performing a couple of tests. This is what happened
Got the new pump in and have about 45 PSI of fuel pressure at idle. When
driving and hitting 6,000 rpm the fuel pressure still drops to 23 PSI. Now
I have spent an additional $190 on a pump and shipping and still nothing.
What else could possibly cause this kind of problem?

 

What happens to pressure at idle when you remove the vacuum line to the regulator?

 

It will go up about 5PSI. I am thinking now that the regulator might be bleeding off pressure to the return?

 

Swapped a stock regulator on and the problem is fixed. Thanks Racetronix for all the help and Aeromotive can suck my a$$. Don't buy one of their piece of **** regulators.