fully built jdm d16. the owner was replacing the headgasket and installing arp head studs, but to remove one of the headstuds he had to remove the FPR. After he was done and everything was reconnected, the car was bogging out, ( staved for fuel). The FP was at 24psi, which is retarded low. So what im wordering is why this has happened?

thanks in advance
Marty