I just installed S4 fuel rails and an aftermarket Fuelab fuel pressure regulator on my 89 Turbo. I have a Supra TT fuel pump and have checked for leaks. I have not found any leaks. I have turned the ignition to on and jumped the diagnostic connector to turn the fuel pump on. For some reason I am only getting up to 30psi of fuel pressure. I reach this relatively quickly and than no matter how far in I screw the adjuster, it doesn't go higher. Any advice? I tried disconnecting the vacuum port, but that shouldn't (and didn't) make any difference since the car isn't running.

 

Are you running the fuel pressure regulator on the stock fuel rail? Can you lower the fuel pressure?

 

Stock S4 fuel rails, adapters and running 5/16 fuel hose everywhere else.

 

is an injector stuck open?

 

as mentioned above,, if the stock FPR is still on the rail and not removed it will behave like this and you will not be able to LOWER the pressure further
( in effect there is 70 psi if measured at the rail and not between regs )

if you only have the one FPR ( as you should ) and it will not go higher then filter may be blocked
or the pump sick
or the pump volts sick,, use a relay

 

Stk regulator should have regulated it to closer to 37-39 psi....key ON engine OFF. See Fuel and Emisisons seciton of the FSM. But at idle and vacuum connected to the stk fpr the pressure should be 28-32 psi.