I can tell you that the AIR system was causing a hunting Idle constantly and a very rich idle condition. After checking almost everything else I finally took the AIR system off. No more Idle hunting and no more super rich Idle.

For arguments sake though, the FPR only had 8 in/Hg of vacuum coming from the divert er valve while now it has a full 15 in/Hg coming from the manifold directly.

With the vacuum line removed I still only get 38 PSI when I talk about primed pressure that is with the ignition on but no motor start so that is all without vacuum.

With motor start the vacuum lowers the FP down to 28 PSI.

I am currently troubleshooting the electrical system as the alternator is bad. Once I install a new one at the end of the month I'm going to move back to the fuel system. I do believe the PO put in a new fuel filter when he did the injectors less than a year ago. So if the pressure is still 38 PSI I'm going to order an AFPR and open the tank to check physical connections and pressure at the pump. The PO also said he removed the metal fuel lines back in 2004 and cleaned them thoroughly with a pipe snake.

I believe this problem will be between a electrical connection issue and possible a clogged sock, worst case failing pump, since that is the original fuel pump and the car has about 96 thousand miles on it now.

 

My hunch was perhaps the diverter valve was faulty and dumping air into the exhaust UPSTREAM of the O2 sensor and giving it a false lean reading and causing the ECM to dump fuel into the system.

Sounds like an obstruction in the pump or a faulty check valve or the pump is dying. Time to give Racetronix a call.

Way too little pressure

Perhaps the alternator is NOT supplying enough power to the pump. Can you test it by hooking up a 12V source to the pump directly?