Cadillac Repair Questions? Ask a Mechanic for Answers ASAP
Hello I will help you with your question,
If the fuel return is blocked off and the pressure comes up to 80 psi or so the pressure regulator is what needs to be replaced. You can check the vacuum line to the regulator(it is on the fuel rail) to see if you have fuel in it. It should be dry, if you do find fuel then replace the rergulator.
Last check is to be sure you have the full 12 volts to the pump, if you have low voltage you will have low pressure.
Let me know what I can do to help you with this