I happen to have a fuel pressure regulator of a petrol car lying around left by the previous owner and suspect that it might be still good, since the previous owner was just changing parts randomly hoping to fix a certain problem. How would one check if the regulator is still good for use?
As I understand the main cause of FPR failure is a ruptured diaphragm inside the metal casing that separates vacuum side from fuel side causing petrol leakage into the vacuum pipe. Does that mean if I blow on the vacuum inlet and no air leaks through - the membrane is still good?